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Save time diagnosing skin diseases with Dermatopathology, edited by Drs. Nooshin Brinster, Vincent Liu, Hafeez Diwan, and Phillip McKee. Part of the High-Yield Pathology Series, this title is designed to help you review the key pathologic features of skin disease, recognize the classic look of each disease, and quickly confirm your diagnosis. Its templated format, excellent color photographs, concise bulleted text, and authoritative content, will help you accurately identify more than 400 skin conditions.

  • Find information quickly and easily with a templated, easy-to-reference format.
  • Confirm your diagnoses with excellent color photographs that demonstrate the classic appearance of each disease.
  • Find the answers you need fast with concise bulleted text.
  • Depend on authoritative information from leading experts in the field.


Acné rosacea
Balanitis plasmacellularis
Necrobiotic xanthogranuloma
Pityrosporum folliculitis
Colloid milium
Urticarial vasculitis
Cutaneous small-vessel vasculitis
Pancreatic panniculitis
Lichen striatus
Erythema dyschromicum perstans
Inflammatory linear verrucous epidermal nevus
Eosinophilic cellulitis
IgA pemphigus
Linear IgA bullous dermatosis
Fixed drug reaction
Acute generalized exanthematous pustulosis
Herpes simplex
Drug-induced lichenoid reaction
Transient neonatal pustular melanosis
Alopecia mucinosa
Neutrophilic eccrine hidradenitis
Chondrodermatitis nodularis chronica helicis
Reactive perforating collagenosis
Elastosis perforans serpiginosa
Lupus erythematosus panniculitis
Epidermolysis bullosa acquisita
Pemphigus vegetans
Pemphigus erythematosus
Pemphigus foliaceus
Dermatitis herpetiformis
Lupus erythematosus
Erythema elevatum diutinum
Rheumatoid nodule
Lichen nitidus
Verruca plana
Nephrogenic systemic fibrosis
Cicatricial pemphigoid
Gestational pemphigoid
Transient acantholytic dermatosis
Papular mucinosis
Subcutaneous fat necrosis of the newborn
Pityriasis lichenoides
Bacillary angiomatosis
Erythema annulare centrifugum
Necrolytic migratory erythema
Radiation dermatitis
Hailey?Hailey disease
Androgenic alopecia
Granuloma annulare
Keratosis follicularis
Degos disease
Pretibial myxedema
Necrobiosis lipoidica
Sweet's syndrome
Lupus vulgaris
Pseudoxanthoma elasticum
Polymorphous light eruption
Erythema nodosum
Bullous pemphigoid
Nodular vasculitis
Atopic dermatitis
Pityriasis rubra pilaris
Meleda disease
X-linked ichthyosis
Granuloma faciale
Actinic keratosis
Stasis dermatitis
Lichen sclerosus
Pityriasis rosea
Polyarteritis nodosa
Calcinosis cutis
Erythema multiforme
Toxic epidermal necrolysis
Lichen planopilaris
Lichen planus
Henoch?Schönlein purpura
Epidermolysis bullosa
Epidermolytic hyperkeratosis
Lamellar ichthyosis
Ichthyosis vulgaris
Hidradenitis suppurativa
Graft-versus-host disease
Porphyria cutanea tarda
Seborrhoeic dermatitis
Granuloma inguinale
Sarcoptes scabiei
Plantar wart
Alpha 1-antitrypsin deficiency
Varicella zoster virus
Necrotizing fasciitis
Orf (disease)
Neutrophil granulocyte
Antiphospholipid syndrome
Alopecia areata
Acne vulgaris
Crohn's disease
Giant cell arteritis
Systemic scleroderma
Pyoderma gangrenosum
Molluscum contagiosum


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High-Yield Pathology
Nooshin K. Brinster, MD
Assistant Professor, Departments of Pathology and
Dermatology, Director of Dermatopathology Services, Virgina
Commonwealth University Medical Center, Richmond,
Vincent Liu, MD
Clinical Associate Professor, Departments of Dermatology and
Pathology, University of Iowa Carver College of Medicine,
Iowa City, Iowa
A. Hafeez Diwan, MD, PhD
Associate Professor and Director of Dermatopathology,
Departments of Pathology & Immunology and Dermatology,
Baylor College of Medicine, Houston, Texas
Phillip H. McKee, MD, FRCPath
Formerly Associate Professor of Pathology and Director,
Division of Dermatopathology, Department of Surgical
Pathology, Brigham and Women’s Hospital and Harvard
Medical School, Boston, Massachusetts
S a u n d e r sFront Matter
High-Yield Pathology Dermatopathology
Nooshin K. Brinster, MD
Assistant Professor, Departments of Pathology and Dermatology, Director
of Dermatopathology Services, Virgina Commonwealth University Medical
Center, Richmond, Virginia
Vincent Liu, MD
Clinical Associate Professor, Departments of Dermatology and Pathology,
University of Iowa Carver College of Medicine, Iowa City, Iowa
A. Hafeez Diwan, MD, PhD
Associate Professor and Director of Dermatopathology, Departments of
Pathology & Immunology and Dermatology, Baylor College of Medicine,
Houston, Texas
Phillip H. McKee, MD, FRCPath
Formerly Associate Professor of Pathology and, Director, Division of
Dermatopathology, Department of Surgical Pathology, Brigham and
Women's Hospital and Harvard Medical School, Boston, Massachusetts?
1600 John F. Kennedy Blvd.
Ste 1800
Philadelphia, PA 19103-2899
DERMATOPATHOLOGY ISBN: 978-1-4160-9976-5
Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
No part of this publication may be reproduced or transmitted in any form or
by any means, electronic or mechanical, including photocopying, recording, or
any information storage and retrieval system, without permission in writing from
the publisher. Details on how to seek permission, further information about the
Publisher's permissions policies and our arrangements with organizations such as
the Copyright Clearance Center and the Copyright Licensing Agency, can be found
at our website:
This book and the individual contributions contained in it are protected under
copyright by the Publisher (other than as may be noted herein).
Knowledge and best practice in this eld are constantly changing. As new
research and experience broaden our understanding, changes in research
methods, professional practices, or medical treatment may become necessary.
Practitioners and researchers must always rely on their own experience and
knowledge in evaluating and using any information, methods, compounds, or
experiments described herein. In using such information or methods they should
be mindful of their own safety and the safety of others, including parties for
whom they have a professional responsibility.
With respect to any drug or pharmaceutical products identi ed, readers are
advised to check the most current information provided (i) on procedures
featured or (ii) by the manufacturer of each product to be administered, to verify
the recommended dose or formula, the method and duration of administration,
and contraindications. It is the responsibility of practitioners, relying on their
own experience and knowledge of their patients, to make diagnoses, to determine
dosages and the best treatment for each individual patient, and to take all
appropriate safety precautions.
To the fullest extent of the law, neither the Publisher nor the authors,contributors, or editors, assume any liability for any injury and/or damage to
persons or property as a matter of products liability, negligence or otherwise, or
from any use or operation of any methods, products, instructions, or ideas
contained in the material herein.
Library of Congress Cataloging-in-Publication Data or Control Number
Dermatopathology/Nooshin K. Brinster… [et al.].
p.; cm. -- (High-yield pathology)
Includes index.
ISBN 978-1-4160-9976-5 (hardcover: alk. paper)
1. Skin--Diseases--Handbooks, manuals, etc. 2.
Skin--Pathophysiology-Handbooks, manuals, etc. I. Brinster, Nooshin K. II. Series: High-yield pathology.
[DNLM: 1. Skin Diseases--Handbooks. 2. Skin--pathology--Handbooks. WR 39
H638 2010]
RL95.D52 2010
616.5’071--dc22 2010019232
Publishing Director: William Schmitt
Senior Developmental Editor: Andrew Hall
Publishing Services Manager: Patricia Tannian
Team Manager: Radhika Pallamparthy
Senior Project Manager: Kristine Feeherty
Project Manager: Antony Prince
Design Direction: Steven Stave
Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1Dedication
To my love, Derek, and our four smiling faces: Layla, Maya, Neda, and Ella. No
matter what …
Nooshin Brinster
To my absolutely wonderful wife, Saba, my two children, my parents, and my three
Hafeez Diwan
To all the patients who grace us, the teachers who inspire us, the students who
challenge us, and the families who fulfill us, this book is for you.
Vince Liu
To Gracie and my four children, whose lives revolve around dermatopathology!
Phillip McKee*
High-Yield Pathology, with access to, is a new series of
pathology textbooks providing quick reference for the busy pathologist and
student. We are honored to have this dermatopathology textbook as the rst
volume in the series.
The study of dermatopathology requires appreciation and understanding of the
“gross” disease, that is, the clinical aspect of cutaneous disorders, as well as the
histological ndings. By integrating both pathological and clinical features, one is
able to arrive at a meaningful diagnosis. With this in mind, D e r m a t o p a t h o l o g y is
organized by histological patterns, further classi ed by disease entity. Clinical and
pathological features of each entity are presented and, where relevant, clinical
photographs are provided. Several pathological photographs are included of each
disease, including immunohistochemical and immuno uorescence, to illustrate the
many faces and phases of each disease. Furthermore, the text is presented in a
bulleted format to facilitate quick reference and learning at the microscope. We
hope that it will provide valuable and practical information for general
pathologists, dermatopathologists, and residents and fellows alike.
Nooshin K. Brinster, MD
Vincent Liu, MD
A. Hafeez Diwan, MD, PhD
Phillip H. McKee, MD, FRCPath


D e r m a t o p a t h o l o g y is a book whose creation and ful llment would not have been
possible without the unwavering leadership of Phillip McKee. His highest standards
and immeasurable dedication are inspiring and matched only by his passion and
sense of humor. It has been a gift to work with and learn from a master. I am also
thankful to my old friend, Vince Liu, who invited me to join the project.
I am in debt to the dermatology residents and faculty of the Medical College of
Virginia who have provided me with the many clinical photographs and skin biopsies
that have found their way into this textbook. I have also been fortunate to have the
administrative support of Jeanette MacFarland and Carol Burney, who have always
been ready to help, however short the notice may have been.
I am extremely grateful to the group at Elsevier publishing, including William
Schmitt, publishing director; Andrew Hall, developmental editor; Kristine Feeherty,
project manager; and Steve Stave, manager of design.
The support of my family has been critical. My parents, Masoud and Vida, have
championed my every endeavor, from childhood until today, with much love. I am
most grateful for the love and guidance of my beloved husband, Derek, and for our
dear daughters, Layla, Maya, Neda, and Ella. They have tolerated the many long
hours (mostly after bedtime) spent in writing the book. I am particularly thankful
that our latest addition demonstrated an uncanny sense of timing by delaying her
arrival into this world until the book was complete.
Nooshin K. Brinster
A work of this kind does not happen without the help of many. First, I am
grateful for all the patients I have been privileged to have known. Second, I am
indebted to all those who have taught me the art and science of dermatology and
dermatopathology. Third, I owe a great deal to all the medical students, residents,
and fellows who have inspired my appreciation for teaching. Fourth, many thanks
go to Chris Huber for her invaluable secretarial assistance. And nally, for her
un agging support through the tremendous sacri ce of this endeavor, a special
thank you to Paula.
Vince Liu
I would like to thank the following colleagues and friends for their help:
Jonathan Curry, Doina S. Ivan, Alexander J. Lazar, Daniel Ostler, Jose Plaza, Victor
G. Prieto, Ronald P. Rapini, Carlos Torres-Cabala, Wei Lien-Wang, and Darren
Whittemore. Doina Ivan was especially helpful in the preparation of the chapter on

Cutaneous Metastases—she added signi cantly to, and vastly improved, this section.
And a special thanks to Saba, Sara, and Hasan, who tolerated and supported me on
many weekends and evenings when I was doing my Greta Garbo impersonation,
wanting to be alone for extended periods of time to work on this book.
Hafeez Diwan
I am indebted to Bill Schmitt from Elsevier, who rst thought of this concept,
and to Andy Hall (also of Elsevier), whose patience and support throughout the
preparation of this book have been unwavering. It has been a pleasure working on
the project with Nooshin, Vince, and Hafeez, although my role has been limited to
editing (sometimes quite a lot!) and photography. As always, I learn much from
others. I also am extremely grateful to Eduardo Calonje, Alex Lazar, Thomas Brenn,
Wayne Grayson, and Iskander Chaudhry, who continually supply me with
fascinating cases to study and photographs for the various book projects that
dominate my life. Finally and of greatest importance, I would never achieve
anything if it were not for the patience and support of Gracie, who―in addition to
being my wife, soul mate, and closest of friends―never wavers in her uphill battle of
keeping me on the right path. Sometimes she finds this a Herculean task!
Phillip McKee
The authors are grateful to the following friends who so kindly contributed
cases: M Avram, F Awadalla, D Barber, C Baum, M Blanes, T Brenn, E Calonje, I
Chaudhry, J Cohen, G Dorer, L Edsall, A Farrajoli, S Granter, W Grayson, B Horvath,
E Hudgins, D Jones, B Kockentiet, A Lazar, PE LeBoit, S Lyle, M Maiberger, SR Mays,
F McMullen, D Metze, M Michal, J Nunley, JC Pascual, S Peck, L Requena, M Saeb, A
Schiedel, D Slater, B Swick, I Van den Berghe, K Vu, D Whittemore, S-B Woo, L
Yarbrough, and B Zelger.
The authors also thank the late NP Smith.Table of Contents
Front Matter
I: Inflammatory Dermatitis
A: Spongiotic Dermatitis
Chapter 1: Atopic Dermatitis
Chapter 2: Seborrheic Dermatitis
Chapter 3: Allergic Contact Dermatitis
Chapter 4: Dyshidrotic Eczema (Pompholyx)
Chapter 5: Stasis Dermatitis
Chapter 6: Spongiotic Drug Eruption
Chapter 7: Arthropod Bite Reaction
Chapter 8: Incontinentia Pigmenti (Bloch-Sulzberger Syndrome)
Chapter 9: Pityriasis Rosea
Chapter 10: Photosensitive (Phototoxic/Photoallergic) Dermatitis
B: Psoriasiform and Pustular Dermatitis
Chapter 11: Psoriasis
Chapter 12: Reiter’s Syndrome
Chapter 13: Pityriasis Rubra Pilaris
Chapter 14: Subcorneal Pustular Dermatosis
Chapter 15: Acute Generalized Exanthematous Pustulosis
Chapter 16: Transient Neonatal Pustular Melanosis
Chapter 17: Lichen Simplex Chronicus and Prurigo NodularisChapter 18: Inflammatory Linear Verrucous Epidermal Nevus
C: Interface Dermatitis
Chapter 19: Erythema Multiforme
Chapter 20: Toxic Epidermal Necrolysis/Stevens-Johnson Syndrome
Chapter 21: Lupus Erythematosus
Chapter 22: Dermatomyositis
Chapter 23: Graft-Versus-Host Disease (GVHD)
Chapter 24: Interface Dermatitis of HIV Infection
Chapter 25: Pityriasis Lichenoides
D: Lichenoid Dermatitis
Chapter 26: Lichen Planus
Chapter 27: Lichenoid Drug Reaction
Chapter 28: Fixed Drug Eruption
Chapter 29: Lichen Striatus
Chapter 30: Lichen Nitidus
Chapter 31: Erythema Dyschromicum Perstans (Ashy Dermatosis)
Chapter 32: Lichenoid Keratosis
E: Acantholytic Disorders
Chapter 33: Pemphigus Foliaceus
Chapter 34: Pemphigus Erythematosus
Chapter 35: IgA Pemphigus
Chapter 36: Pemphigus Vulgaris
Chapter 37: Pemphigus Vegetans
Chapter 38: Paraneoplastic Pemphigus
Chapter 39: Darier’s Disease (Keratosis Follicularis)
Chapter 40: Hailey-Hailey Disease (Familial Benign Pemphigus)
Chapter 41: Grover’s Disease (Transient Acantholytic Dermatosis)
F: Subepidermal Vesicular Dermatitis
Chapter 42: Bullous Pemphigoid
Chapter 43: Pemphigoid (Herpes) GestationisChapter 44: Mucosal (Cicatricial) Pemphigoid
Chapter 45: Epidermolysis Bullosa Acquisita
Chapter 46: Epidermolysis Bullosa Congenita
Chapter 47: Dermatitis Herpetiformis
Chapter 48: Linear IgA Disease
Chapter 49: Porphyria Cutanea Tarda
Chapter 50: Pseudoporphyria
G: Granulomatous Dermatitis
Chapter 51: Granuloma Annulare
Chapter 52: Necrobiosis Lipoidica
Chapter 53: Rheumatoid Nodule
Chapter 54: Palisaded Neutrophilic and Granulomatous Dermatitis
Chapter 55: Necrobiotic Xanthogranuloma
Chapter 56: Sarcoidosis
Chapter 57: Cutaneous Crohn’s Disease
Chapter 58: Foreign-Body Granulomata
H: Superficial and Deep Perivascular Dermatitis
Chapter 59: Erythema Annulare Centrifugum
Chapter 60: Urticaria
Chapter 61: Polymorphous Light Eruption
I: Folliculitis, Perifolliculitis, and Inflammation of the Sweat Apparatus
Chapter 62: Acne Vulgaris
Chapter 63: Rosacea
Chapter 64: Hidradenitis Suppurativa
Chapter 65: Acne Agminata
Chapter 66: Folliculitis
Chapter 67: Eosinophilic Folliculitis
Chapter 68: Neutrophilic Eccrine Hidradenitis
Chapter 69: Acne Keloidalis Nuchae
J: AlopeciaChapter 70: Alopecia Areata
Chapter 71: Androgenetic Alopecia
Chapter 72: Dissecting Cellulitis (Dissecting Folliculitis)
Chapter 73: Follicular Degeneration Syndrome
Chapter 74: Folliculitis Decalvans
Chapter 75: Lichen Planopilaris (LPP) and Frontal Fibrosing Alopecia
K: Vasculitis and Vasculopathy
Chapter 76: Leukocytoclastic Vasculitis (LCV)
Chapter 77: Henoch-Schönlein Purpura (HSP)
Chapter 78: Urticarial Vasculitis
Chapter 79: Granuloma Faciale
Chapter 80: Erythema Elevatum Diutinum
Chapter 81: Polyarteritis Nodosa
Chapter 82: Wegener’s Granulomatosis
Chapter 83: Churg-Strauss Syndrome (Allergic Granulomatosis with
Chapter 84: Disseminated Intravascular Coagulopathy (DIC)
Chapter 85: Cryoglobulinemia
Chapter 86: Antiphospholipid Antibody Syndrome
Chapter 87: Coumadin (Warfarin) Necrosis
Chapter 88: Cholesterol Crystal Embolism
Chapter 89: Giant Cell (Temporal) Arteritis
Chapter 90: Atrophie Blanche (Livedoid Vasculitis)
Chapter 91: Lymphocytic Vasculitis
Chapter 92: Perniosis
Chapter 93: Degos’ Disease (Malignant Atrophic Papulosis)
Chapter 94: Pigmented Purpura
L: Fibrosing/Sclerosing Dermatitis
Chapter 95: Morphea
Chapter 96: Scleroderma (Systemic Sclerosis)
Chapter 97: Lichen SclerosusChapter 98: Nephrogenic Systemic Fibrosis
Chapter 99: Radiation Dermatitis
M: Panniculitis
Chapter 100: Erythema Nodosum
Chapter 101: α Antitrypsin Deficiency–Associated Panniculitis
Chapter 102: Pancreatic Panniculitis
Chapter 103: Subcutaneous Fat Necrosis of the Newborn
Chapter 104: Nodular Vasculitis/Erythema Induratum
Chapter 105: Lupus Profundus
Chapter 106: Factitial and Traumatic Fat Necrosis
Chapter 107: Lipodermatosclerosis (Sclerosing Panniculitis)
Chapter 108: Infective Panniculitis
N: Other Inflammatory Dermatoses
Chapter 109: Sweet’s Syndrome (Acute Febrile Neutrophilic Dermatosis)
Chapter 110: Pyoderma Gangrenosum
Chapter 111: Behçet’s Disease
Chapter 112: Eosinophilic Cellulitis (Wells’ Syndrome)
Chapter 113: Eosinophilic Fasciitis (Schulman’s Syndrome)
Chapter 114: Zoon’s Balanitis
O: Disorders of Keratinization
Chapter 115: Ichthyosis Vulgaris
Chapter 116: X-Linked Recessive Ichthyosis
Chapter 117: Lamellar Ichthyosis
Chapter 118: Congenital Bullous Ichthyosiform Erythroderma
Chapter 119: Palmoplantar Keratoderma (PPK)
Chapter 120: Porokeratosis
Chapter 121: Axillary Granular Parakeratosis
II: Infectious Dermatitis
A: Viral Infections
Chapter 122: Verruca VulgarisChapter 123: Verruca Plantaris (Plantar Wart)
Chapter 124: Verruca Plana (Plane Wart)
Chapter 125: Condyloma Acuminatum
Chapter 126: Molluscum Contagiosum
Chapter 127: Herpes Simplex
Chapter 128: Varicella-Zoster Virus (VZV)
Chapter 129: ORF (Ecthyma Contagiosum)
B: Bacterial Infections
Chapter 130: Impetigo
Chapter 131: Staphylococcal–Scalded Skin Syndrome
Chapter 132: Necrotizing Fasciitis
Chapter 133: Ecthyma
Chapter 134: Bacillary Angiomatosis
Chapter 135: Actinomycosis
Chapter 136: Granuloma Inguinale
Chapter 137: Anthrax
Chapter 138: Corynebacterial Infections
Chapter 139: Lyme Disease
Chapter 140: Syphilis
Chapter 141: Lupus Vulgaris
Chapter 142: Atypical Mycobacterial Infections
Chapter 143: Leprosy
C: Fungal Infections
Chapter 144: Dermatophytosis
Chapter 145: Tinea Versicolor
Chapter 146: Candida
Chapter 147: Pityrosporum Folliculitis
Chapter 148: Mycetoma
Chapter 149: North American Blastomycosis
Chapter 150: HistoplasmosisChapter 151: Cryptococcosis
Chapter 152: Coccidioidomycosis
Chapter 153: Paracoccidioidomycosis (South American Blastomycosis)
Chapter 154: Chromoblastomycosis (Chromomycosis)
Chapter 155: Phaeohyphomycosis
Chapter 156: Sporotrichosis
Chapter 157: Aspergillosis
Chapter 158: Zygomycosis
D: Other Infections
Chapter 159: Protothecosis
Chapter 160: Rhinosporidiosis
Chapter 161: Leishmaniasis
Chapter 162: Amoebiasis Cutis
Chapter 163: Onchocerciasis
Chapter 164: Schistosomiasis (Bilharzia)
Chapter 165: Scabies
Chapter 166: Tungiasis
III: Noninflammatory Dermatoses
A: Metabolic and Degenerative Disorders
Chapter 167: Necrolytic Migratory Erythema
Chapter 168: Acrodermatitis Enteropathica
Chapter 169: Cutaneous Amyloidosis
Chapter 170: Adult Colloid Milium
Chapter 171: Juvenile Colloid Milium
Chapter 172: Gout
Chapter 173: Lichen Myxedematosus/Scleromyxedema
Chapter 174: Scleredema (Buschke)
Chapter 175: Pretibial Myxedema
Chapter 176: Follicular Mucinosis
Chapter 177: Calcinosis CutisChapter 178: Calciphylaxis
Chapter 179: Chondrodermatitis Nodularis Helicis
B: Diseases of Collagen and Elastic Tissue
Chapter 180: Pseudoxanthoma Elasticum
Chapter 181: Elastosis Perforans Serpiginosa
Chapter 182: Reactive Perforating Collagenosis
Chapter 183: Kyrle’s Disease (Hyperkeratosis Follicularis et Parafollicularis
in Cutem Penetrans)
C: Disorders of Pigmentation
Chapter 184: Vitiligo
Chapter 185: Drug-Induced Pigmentation
IV: Neoplasms
A: Cysts and Pseudocysts
Chapter 186: Dilated Pore of Winer
Chapter 187: Epidermoid (Infundibular) Cyst
Chapter 188: Pilar (Trichilemmal) Cyst
Chapter 189: Proliferating Pilar Tumor
Chapter 190: Steatocystoma
Chapter 191: Eruptive Vellus Hair Cyst
Chapter 192: Hidrocystoma
Chapter 193: Cutaneous Ciliated Cyst
Chapter 194: Dermoid Cyst
Chapter 195: Digital Myxoid (Mucous) Cyst
B: Melanocytic Neoplasms
Chapter 196: Ephelis
Chapter 197: Lentigo
Chapter 198: Ink Spot Lentigo
Chapter 199: Labial Melanotic Macule
Chapter 200: Melanocytic Nevus
Chapter 201: Acral Nevus
Chapter 202: Congenital Melanocytic NevusChapter 203: Halo Nevus (Sutton’s Nevus)
Chapter 204: Balloon Cell Nevus
Chapter 205: Recurrent (Persistent) Nevus (Pseudomelanoma)
Chapter 206: Atypical Genital (Milk-Line, Flexural) Nevus (Nevus of Special
Anatomic Sites)
Chapter 207: Dysplastic Nevus
Chapter 208: Spitz Nevus
Chapter 209: Pigmented Spindle Cell Nevus (Reed Nevus)
Chapter 210: Nevus of Ota (Nevus Fusoceruleus Ophthalmomaxillaris) and
Nevus of Ito (Nevus Fusoceruleus Acromioclavicularis)
Chapter 211: Blue Nevus
Chapter 212: Combined Nevus
Chapter 213: Deep Penetrating Nevus
Chapter 214: Melanoma
C: Keratinocytic Neoplasms
Chapter 215: Epidermal Nevus
Chapter 216: Seborrheic Keratosis
Chapter 217: Inverted Follicular Keratosis (Irritated Seborrheic Keratosis)
Chapter 218: Stucco Keratosis
Chapter 219: Borst-Jadassohn Phenomenon
Chapter 220: Large Cell Acanthoma
Chapter 221: Acantholytic Acanthoma
Chapter 222: Warty Dyskeratoma
Chapter 223: Clear Cell Acanthoma
Chapter 224: Actinic Keratosis
Chapter 225: Squamous Cell Carcinoma in Situ
Chapter 226: Squamous Cell Carcinoma
Chapter 227: Keratoacanthoma
Chapter 228: Verrucous Carcinoma
Chapter 229: Basal Cell Carcinoma
D: Follicular NeoplasmsChapter 230: Trichoepithelioma
Chapter 231: Desmoplastic Trichoepithelioma
Chapter 232: Trichilemmoma
Chapter 233: Desmoplastic Trichilemmoma
Chapter 234: Tumor of the Follicular Infundibulum (Infundibuloma)
Chapter 235: Pilar Sheath Acanthoma
Chapter 236: Basaloid Follicular Hamartoma
Chapter 237: Trichoblastoma
Chapter 238: Trichofolliculoma
Chapter 239: Pilomatrixoma
Chapter 240: Lymphadenoma Cutis
Chapter 241: Trichilemmal Carcinoma
Chapter 242: Matrical Carcinoma (Pilomatrix Carcinoma, Malignant
E: Sebaceous Neoplasms
Chapter 243: Nevus Sebaceus of Jadassohn (Organoid Nevus)
Chapter 244: Sebaceous Hyperplasia
Chapter 245: Sebaceous Adenoma
Chapter 246: Sebaceoma
Chapter 247: Sebaceous Carcinoma
F: Eccrine/Apocrine Neoplasms
Chapter 248: Poroma
Chapter 249: Dermal Duct Tumor
Chapter 250: Eccrine Syringofibroadenoma (Acrosyringeal Nevus)
Chapter 251: Syringoma
Chapter 252: Nodular Hidradenoma
Chapter 253: Chondroid Syringoma (Mixed Tumor)
Chapter 254: Eccrine Spiradenoma
Chapter 255: Cylindroma
Chapter 256: Syringocystadenoma Papilliferum
Chapter 257: Hidradenoma PapilliferumChapter 258: Tubular Apocrine Adenoma (Papillary Tubular Adenoma)
Chapter 259: Papillary Eccrine Adenoma
Chapter 260: Microcystic Adnexal Carcinoma
Chapter 261: Adenoid Cystic Carcinoma
Chapter 262: Eccrine Porocarcinoma
Chapter 263: Primary Cutaneous Mucinous Carcinoma
Chapter 264: Hidradenocarcinoma (Malignant Acrospiroma, Clear Cell
Chapter 265: Eccrine Ductal Carcinoma
Chapter 266: Aggressive Digital Papillary Adenocarcinoma
Chapter 267: Apocrine Carcinoma
G: Fibrous, Fibrohistiocytic, and Myofibroblastic Neoplasms
Chapter 268: Hypertrophic Scar
Chapter 269: Keloid
Chapter 270: Fibrous Papule
Chapter 271: Acrochordon (Fibroepithelial Polyp, Skin Tag)
Chapter 272: Acquired Digital Fibrokeratoma
Chapter 273: Superficial Angiomyxoma
Chapter 274: Palmar Fibromatosis (Dupuytren’s Contracture)
Chapter 275: Nodular Fasciitis
Chapter 276: Elastofibroma
Chapter 277: Fibroma of Tendon Sheath
Chapter 278: Giant Cell Tumor of Tendon Sheath
Chapter 279: Inclusion Body Fibromatosis (Infantile Digital Fibromatosis)
Chapter 280: Fibrous Hamartoma of Infancy
Chapter 281: Sclerotic Fibroma (Storiform Collagenoma)
Chapter 282: Infantile Myofibromatosis and Solitary Myofibroma
Chapter 283: Myoepithelioma
Chapter 284: Solitary Fibrous Tumor
Chapter 285: Dermatofibroma (Fibrous Histiocytoma)
Chapter 286: Cellular Fibrous HistiocytomaChapter 287: Atypical Fibrous Histiocytoma
Chapter 288: Dermatomyofibroma
Chapter 289: Dermatofibrosarcoma Protuberans (DFSP)
Chapter 290: Giant Cell Fibroblastoma
Chapter 291: Atypical Fibroxanthoma
Chapter 292: Superficial Malignant Fibrous Histiocytoma (Superficial
Pleomorphic Sarcoma—NOS)
Chapter 293: Epithelioid Sarcoma
H: Vascular Neoplasms
Chapter 294: Intravascular Papillary Endothelial Hyperplasia (Masson’s
Chapter 295: Lobular Capillary Hemangioma (Pyogenic Granuloma)
Chapter 296: Port Wine Stain
Chapter 297: Infantile Hemangioma (Strawberry Nevus, Juvenile
Hemangioma, Infantile Hemangioendothelioma)
Chapter 298: Cavernous Hemangioma
Chapter 299: Arteriovenous Hemangioma (Arteriovenous Malformation,
Cirsoid Aneurysm)
Chapter 300: Cherry Hemangioma (Senile Hemangioma, Campbell de
Morgan Spot)
Chapter 301: Angiokeratoma
Chapter 302: Hobnail Hemangioma (Targetoid Hemosiderotic
Chapter 303: Spindle Cell Hemangioma
Chapter 304: Multinucleate Cell Angiohistiocytoma
Chapter 305: Epithelioid Hemangioma (Angiolymphoid Hyperplasia with
Chapter 306: Reactive Angioendotheliomatosis
Chapter 307: Lymphangioma Circumscriptum
Chapter 308: Glomus Tumor/Glomangioma
Chapter 309: Myopericytoma
Chapter 310: Epithelioid HemangioendotheliomaChapter 311: Kaposi’s Sarcoma
Chapter 312: Cutaneous Angiosarcoma
Chapter 313: Epithelioid Angiosarcoma
I: Neural-Neuroendocrine Neoplasms
Chapter 314: Traumatic Neuroma
Chapter 315: Morton’s Neuroma (Metatarsalgia)
Chapter 316: Neurofibroma
Chapter 317: Schwannoma (Neurilemmoma)
Chapter 318: Palisaded Encapsulated Neuroma (Solitary Circumscribed
Chapter 319: Granular Cell Tumor
Chapter 320: Neurothekeoma (Myxoid Neurothekeoma, Dermal Nerve
Sheath Myxoma)
Chapter 321: Cellular Neurothekeoma
Chapter 322: Perineurioma
Chapter 323: Nasal Glioma
Chapter 324: Malignant Peripheral Nerve Sheath Tumor
(Neurofibrosarcoma, Malignant Schwannoma)
Chapter 325: Merkel Cell Carcinoma
J: Muscular Neoplasms
Chapter 326: Leiomyoma and Angioleiomyoma
Chapter 327: Leiomyosarcoma
K: Adipose, Osseous, and Cartilaginous Neoplasms
Chapter 328: Lipoma
Chapter 329: Angiolipoma
Chapter 330: Spindle Cell Lipoma
Chapter 331: Pleomorphic Lipoma
Chapter 332: Liposarcoma
Chapter 333: Osteoma Cutis
Chapter 334: Soft Tissue Chondroma
L: T-Cell (and NK/T-Cell) NeoplasmsChapter 335: T-Cell Pseudolymphoma
Chapter 336: Chronic Actinic Dermatitis (Actinic Reticuloid)
Chapter 337: Mycosis Fungoides
Chapter 338: Sézary Syndrome
Chapter 339: Pagetoid Reticulosis
Chapter 340: Granulomatous Slack Skin
Chapter 341: Primary Cutaneous Aggressive Epidermotropic CD8-Positive
Cytotoxic T-Cell Lymphoma
Chapter 342: Lymphomatoid Papulosis
Chapter 343: Anaplastic Large Cell Lymphoma (ALCL)
Chapter 344: Subcutaneous Panniculitis-Like T-Cell Lymphoma
Chapter 345: Adult T-Cell Leukemia/Lymphoma (ATLL)
Chapter 346: Extranodal NK/T-Cell Lymphoma, Nasal Type
Chapter 347: Gamma/Delta T-Cell Lymphoma
M: B-Cell Neoplasms
Chapter 348: B-Cell Pseudolymphoma (Cutaneous Lymphoid Hyperplasia)
Chapter 349: Primary Cutaneous Marginal Zone B-Cell
Chapter 350: Primary Cutaneous Follicle Center Lymphoma (PCFCL)
Chapter 351: Primary Cutaneous Diffuse Large B-Cell Lymphoma
Chapter 352: Intravascular B-Cell Lymphoma
Chapter 353: Lymphomatoid Granulomatosis
N: Xanthomatous, Histiocytic, Mast Cell, Myeloid Neoplasms, and
Plasma Cell
Chapter 354: Xanthomata
Chapter 355: Xanthogranuloma (Juvenile)
Chapter 356: Xanthoma Disseminatum
Chapter 357: Verruciform Xanthoma
Chapter 358: Rosai-Dorfman Disease
Chapter 359: Reticulohistiocytoma
Chapter 360: Langerhans Cell HistiocytosisChapter 361: Cutaneous Mastocytosis
Chapter 362: Leukemia Cutis
Chapter 363: Plasmacytoma
O: Cutaneous Metastases/Implantation
Chapter 364: Cutaneous Endometriosis
Chapter 365: Cutaneous Metastases
Chapter 366: Extramammary Paget’s Disease
Inflammatory DermatitisA
Spongiotic DermatitisAtopic Dermatitis
• Eczematous dermatitis in individuals as manifestation of atopic diathesis
Clinical features
• Affects those with atopic tendency (associated with allergic rhinitis and asthma)
• Familial predisposition
• Typically arises in infancy or childhood; delayed onset in adulthood less common
• Eczematous reaction pattern with classically dry, scaly, pruritic patches and
• Often symmetrically distributed
• Infancy: extensor involvement
• Childhood: flexural involvement of arms and legs, trunk, face (with sparing of
nose—“headlight sign”)
• With chronicity, lichenification and dyspigmentation occur
Prognosis and treatment
• Lifelong tendency, although many improve over time
• Risk for superinfection (impetiginization or eczema herpeticum)
• Dry skin care important part of management
• Therapeutic regimen includes topical corticosteroids, topical
calcineurininhibitors, antihistamines, systemic immunosuppressives (e.g., methotrexate,
cyclosporine), phototherapy
• Acute: mild acanthosis, epidermal spongiosis, lymphocytic exocytosis, superficial
dermal perivascular lymphohistiocytic infiltrate sometimes accompanied by
• Subacute: parakeratosis, acanthosis, variable epidermal spongiosis, superficial
dermal chronic inflammation
• Chronic: hyperkeratosis, psoriasiform epidermal hyperplasia, hypergranulosis,
spongiosis less prominent or absent
Immunopathology (including immunohistochemistry)
• Not contributory
Main differential diagnoses
• Other spongiotic dermatitides including nummular eczema, contact dermatitis
• Seborrheic dermatitis
• Spongiotic drug eruption
• Dermatophytosis
Fig 1 Atopic dermatitis. Pruritic, dry, scaly, ill-de ned patches symmetrically
distributed in the bilateral antecubital fossae.Fig 2 Atopic dermatitis. Numerous few-millimeter erythematous eczematous
papules, several excoriated, over the left medial thigh.
Fig 3 Atopic dermatitis. Focally crusted, fairly discrete, hyperkeratotic, pink
erythematous, nummular plaque in a patient with atopic dermatitis.
Fig 4 Atopic dermatitis. There is hyperkeratosis, parakeratosis, and psoriasiform
hyperplasia associated with mild spongiosis in this example of subacute atopic
Fig 5 Atopic dermatitis. Intraepidermal Langerhans cell microgranuloma with
surrounding spongiosis.
Fig 6 Atopic dermatitis. Spongiosis and lymphocytic exocytosis.
Fig 7 Atopic dermatitis. In the dermis, there is a lymphocytic in ltrate with an
eosinophil and melanophages.Fig 8 Chronic spongiotic dermatitis. Hyperkeratosis with crusting and acanthosis.
Note the superficial perivascular chronic inflammatory cell infiltrate.
Fig 9 Chronic spongiotic dermatitis. There is parakeratosis and focal spongiosis
with lymphocytic exocytosis.Seborrheic Dermatitis
• Common papulosquamous skin condition affecting sebum-rich areas of the body
Clinical features
• Predilection for whites
• May arise in infancy but more common in adults, beginning with puberty
• Can be particularly prominent in AIDS patients and patients with neurologic
• Greasy, scaling erythema in a seborrheic (sebum-rich) distribution: scalp,
eyebrows, perinasal region, beard area, presternal chest, axillae, and groin
• Scalp involvement prompts patient’s complaint of dandruff and pruritus
• In particularly inflammatory areas, erythematous 2- to 4-mm papules sometimes
• Affected areas can be pruritic or burning
• Erythroderma rare: occurs in AIDS and patients with neurologic disorders
Prognosis and treatment
• Benign process with waxing-waning course
• Topical steroids or topical calcineurin-inhibitors (e.g., tacrolimus, pimecrolimus)
to calm inflammation
• Antiseborrheic shampoos (containing ingredients such as zinc pyrithione,
selenium sulfide, tar preparations, keratolytics)
• Topical or, if indicated, oral, ketoconazole, or other antifungals (e.g., other azoles
or allylamines)
• Certain medications may flare condition (e.g., lithium, buspirone,3
chlorpromazine, gold)
• Occasional superinfection can occur
• Features of subacute spongiotic dermatitis: mildly spongiotic epidermis topped by
mounded parakeratosis (often perifollicular), lymphocytic exocytosis, mild
superficial perivascular infiltrate of lymphocytes, histiocytes, and scattered
• Irregular epidermal hyperplasia
• Intracorneal neutrophilic collections (often perifollicular) may be present
• Intracorneal pityrosporum organisms sometimes found
• Not contributory
Main differential diagnoses
• Other subacute spongiotic conditions
• Psoriasis
Fig 1 Seborrheic dermatitis. Erythema and marked scaling a ecting the beard
area.Fig 2 Seborrheic dermatitis. Hyperkeratosis with characteristic perifollicular
parakeratosis. A superficial perivascular lymphohistiocytic infiltrate is present.
Fig 3 Seborrheic dermatitis. High-power view showing perifollicular
parakeratosis, focal spongiosis, and lymphocytic exocytosis.Allergic Contact Dermatitis
• Cutaneous delayed hypersensitivity reaction to exogenous antigen
Clinical features
• Affects any age, either sex
• Common contactants include nickel, R h u s (uroshiol), fragrance,
neomycin/bacitracin, formaldehyde, quaternium-15
• Eczematous reaction pattern at areas in contact with the offending antigen, so
characteristically linear or in geometric pattern
• Acutely, exposed areas may be weepy, blistering, brightly erythematous
edematous papules and plaques, often with excoriation, sometimes with crusting
• With time, areas become xerotic, develop more prominent scale, and may leave
postinflammatory hyper/hypopigmentation
Prognosis and treatment
• Classically self-limited over days to weeks after removal of causative agent
• Treatment with topical and systemic corticosteroids
• Immunosuppressive treatment may blunt histologic features
• Secondary impetiginization can occur, may require treatment with topical/oral
• A c u t e: prominent epidermal spongiosis often with vesiculation, lymphocytic
exocytosis, conspicuous epidermal Langerhans cells, may form microabscesses,
superficial dermal perivascular lymphohistiocytic infiltrate with eosinophils,
papillary dermal edema• S u b a c u t e: focal parakeratosis, epidermal spongiosis less conspicuous, mild
epidermal hyperplasia, superficial dermal chronic inflammation
• C h r o n i c: focal parakeratosis, psoriasiform epidermal hyperplasia, spongiosis much
less prominent or absent, papillary dermal fibrosis
Immunopathology (including immunohistochemistry)
• Not contributory
Main differential diagnoses
• Other spongiotic dermatitides (e.g., seborrheic dermatitis, spongiotic drug
• Insect bite reaction
• Sézary syndrome
• Mycosis fungoides may resemble the subacute and chronic forms of dermatitis
Fig 1 Allergic contact dermatitis. Florid example of an acute lesion showing
diffuse vesiculation.Fig 2 Allergic contact dermatitis. Eczematous scaly erythematous plaque on the
chest with sharp demarcation at the inferior border, representing allergic contact
dermatitis to perfume.
Fig 3 Allergic contact dermatitis. Fairly well-demarcated plaque formed by a
coalescence of erythematous few-millimeter papules, with areas of focally crusted
erosion in the infraumbilical area as a result of nickel allergy in a belt buckle.
Fig 4 Allergic contact dermatitis. Crusting, psoriasiform hyperplasia, and3
spongiosis with vesiculation.
Fig 5 Allergic contact dermatitis. Spongiosis and marked lymphocytic exocytosis.
Fig 6 Allergic contact dermatitis. Dermal edema with a super cial perivascular
lymphohistiocytic infiltrate. Note the eosinophils.
Fig 7 Allergic contact dermatitis. Conspicuous Langerhans cells.Fig 8 Allergic contact dermatitis. Chronic lesion showing hyperkeratosis, focal
mild parakeratosis, psoriasiform hyperplasia, and fibrosis of the papillary dermis.Dyshidrotic Eczema (Pompholyx)
• Recurrent vesicular dermatitis of the hands and feet
Clinical features
• Most commonly presents in adults in the third to fifth decades of life, but
children, teens, and elderly also affected
• More often seen in females
• No clear racial predilection
• Pruritic eruption of 1- to 2-mm deep-seated, tapioca pudding–like vesicles
embedded in the palms, along the finger sides, and soles
• Background variable scaling erythema
• Hyperhidrosis may be seen
• Typically lasts 2 to 4 weeks, but, not uncommonly, can experience recurrent
• Longitudinal furrowing of nails sometimes occurs
Prognosis and treatment
• Topical (or intralesional or systemic) corticosteroids, topical calcineurin
inhibitors, PUVA (topical soaks or with hand/foot unit) form the mainstay of
• Botulinum toxin now being offered
• Epidermal spongiosis with intraepidermal spongiotic macrovesiculation• Superficial perivascular lymphocytic inflammation
• Occasional eosinophils
Special stains/immunopathology
• Not contributory
Main differential diagnoses
• Dermatophyte infection
• Acute contact dermatitis
Fig 1 Dyshidrotic eczema. Erythematous papulovesicles on the palm.
Fig 2 Dyshidrotic eczema. Scanning view showing multiple large intraepidermal
vesicles.Fig 3 Dyshidrotic eczema. High-power view showing spongiotic vesicle. In view of
the conspicuous neutrophils, a secondary infection should be excluded.Stasis Dermatitis
• Eczematous changes, classically of the lower legs—attributed to venous stasis
(varicose veins)
Clinical features
• Older individuals (generally after fifth decade of life)
• Patients with venous insufficiency (e.g., parous women, patients with chronic
congestive heart failure, patient status—posttrauma or surgery to a lower
• Pruritic and sometimes painful, occasionally weeping, scaling erythema of the
lower legs, often beginning just proximal to the ankles
• Underlying lower extremity edema
• With time, skin assumes violaceous-brown hue related to hemosiderin deposition
• Can become lichenified and acquire very thick retention hyperkeratosis
• Impetiginization with honey-colored crusting or other secondary infection
• Ulceration often occurs, particularly over the medial malleolus
• Advanced stasis changes can give rise to ill-defined, dome-shaped, thick
erythematous to violaceous papules that can resemble vascular tumors
• Atrophie blanche, with porcelain white scarring studded by pinpoint red vascular
macules seen in advanced cases
• Ulcerated chronic lesions may develop nonmelanoma skin cancer
Prognosis and treatment
• Slowly progressive course, can result in secondary infection, ulceration, and/orlipodermatosclerosis
• Topical corticosteroids or calcineurin inhibitors to relieve inflammation
• Measures to counter effects of gravity and provide compression (e.g., leg
elevation, support hose) can help slow progression
• Antiplatelet agents (e.g., aspirin, pentoxifylline)
• For stasis ulcers, Unna boots, porcine grafting, and, sometimes, hyperbaric
oxygen used
• Antibiotics as indicated for cases of superinfection
• Beware allergic contact dermatitis from topical medication
• Variable hyperkeratosis and acanthosis with serous crust
• Epidermal spongiosis overlying superficial perivascular chronic inflammatory cell
• Conspicuous superficial dermal lobular vascular proliferation
• Fibrin deposition
• Dermal fibrosis with hemosiderin deposition
• Not contributory
Main differential diagnosis
• Nummular or atopic dermatitis5
Fig 1 Stasis dermatitis. Lower leg showing scaling erythema with overlying
mammillated plaques and background pitting edema.
Fig 2 Stasis dermatitis. Ill-de ned erythema with relative loss of hair on the lower
Fig 3 Stasis dermatitis. Low-power view showing hyperkeratosis, an irregular
epidermis, and a superficial inflammatory cell infiltrate.
Fig 4 Stasis dermatitis. High-power view showing blood vessel wall brin
deposition. The features of stasis dermatitis often overlap with atrophie blanche.
Fig 5 Stasis dermatitis. Dermal fibrosis as shown in this field is generally present.5
Fig 6 Stasis dermatitis. Note the vascular proliferation.
Fig 7 Stasis dermatitis. Red cell extravasation is conspicuous.
Fig 8 Stasis dermatitis. This eld shows blood vessel wall hyalinization and
hemosiderin deposits.Spongiotic Drug Eruption
• Eczematous cutaneous hypersensitivity reaction to a drug
Clinical features
• Adults and children affected
• Common drugs implicated include antibiotics (e.g., penicillins), sulfa-based
medications, ethylenediamine
• Can be initiated by topical contact sensitization
• Eruption arises upon initial exposure to drug or upon reexposure to medication to
which individual had been previously sensitized
• May be preceded by generalized pruritus
• Diffuse, usually symmetric eczematous, scaling erythematous thin plaques
• Areas of crusted erosions and microvesiculation may be seen
• Dyshidrotic vesicles on palms occur in some cases
• In generalized cases, may mimic erythrodermic atopic dermatitis
Prognosis and treatment
• Discontinuation of culprit medication
• Symptomatic, supportive care (e.g., topical corticosteroids, antihistamines)
• Focal parakeratosis, variable acanthosis
• Lymphocyte exocytosis with spongiosis• Intraepidermal microvesiculation
• Eosinophilic spongiosis occasionally seen
• Cytoid bodies often present
• Superficial perivascular predominantly lymphocytic inflammation with scattered
Special stains/immunopathology
• Not contributory
Main differential diagnoses
• Dermatophyte infection
• Other causes of spongiotic dermatitis (e.g., atopic dermatitis, allergic contact
dermatitis, seborrheic dermatitis)
• Mycosis fungoides
Fig 1 Spongiotic drug eruption. Eczematous scaly erythema of the face thought to
be secondary to antihypertensive medication.Fig 2 Spongiotic drug eruption. There is hyperkeratosis, acanthosis, and mild
spongiosis. A heavy perivascular infiltrate is seen in the superficial dermis.
Fig 3 Spongiotic drug eruption. Note the spongiosis and the presence of
eosinophils.Arthropod Bite Reaction
• Clinicopathologic constellation of findings due to an arthropod bite
Clinical features
• Quite common
• Wide age range
• Secondary to any arthropod including fleas, mosquitoes, bed bugs, mites, ticks,
spiders, bees, wasps
• Solitary or multiple lesions
• Urticarial papules, vesicles, or plaques are possible
• Pruritus
• Punctum may be clinically evident
• Wide anatomic distribution, but some areas (e.g., face and legs) are more
• Source of arthropod may not be clear
• Necrosis in cases of tick bites and spider bites
Prognosis and treatment
• Symptomatic treatment: topical corticosteroids, antihistamines, epinephrine if
severe type I hypersensitivity reaction develops
• Secondary bacterial infection possible
• Some lesions may persist for months, particularly with tick bites and retained
• Anaphylaxis may occur in those who are hypersensitive
• Epidermal necrosis or ulceration
• Variable degree of spongiosis with or without intraepidermal eosinophils
• Subepidermal edema may be evident and can be very marked in severe reactions
• Wedge-shaped infiltrate of neutrophils, lymphocytes, and eosinophils
• Flame figures sometimes seen
• Infiltrate is perivascular (superficial and deep) and interstitial
• Thrombi may be seen in spider bites (brown recluse spider)
• Arthropod mouth parts (e.g., tick) can be seen
• Chronic arthropod bite reactions sometimes show cutaneous lymphoid
hyperplasia, top-heavy infiltrate, and lymphoid follicles with or without germinal
centers (cutaneous B-cell pseudolymphoma, lymphocytoma cutis)
• Eosinophils, plasma cells, giant cells, and granulomata are occasionally seen
Immunopathology/special stains
• CD20 B cells admixed with CD3 T cells in chronic lesions
• Numerous CD30-positive cells may be present
• No evidence of a clonal population in chronic pseudolymphomatous lesions
Main differential diagnoses
• Lymphomatoid papulosis
• Drug reaction
• LymphomaFig 1 Arthropod bite reaction. Clustered erythematous, edematous papules with
central vesicles.
Fig 2 Arthropod bite reaction. This example shows ulceration overlying a zone of
dermal necrosis with retained arthropod parts.
Fig 3 Arthropod bite reaction. Bullous lesion characterized by massive
subepidermal edema.5
Fig 4 Arthropod bite reaction. There is a perivascular in ltrate consisting of
lymphocytes and conspicuous eosinophils.
Fig 5 Arthropod bite reaction. There is a flame figure in the center of the field.
Fig 6 Arthropod bite reaction. Low-power view of a chronic lesion showing a
pseudolymphomatous infiltrate. A follicular architecture is evident.5
Fig 7 Arthropod bite reaction. High-power view of a follicle showing mitotic
activity and tingible body macrophages.
Fig 8 Arthropod bite reaction. The interfollicular in ltrate consists of
lymphocytes, histiocytes, and conspicuous plasma cells.Incontinentia Pigmenti (Bloch-Sulzberger
• Genodermatosis characterized by progressive cutaneous blistering, warty papules,
and dyspigmentation in a blaschkoid arrangement, caused by mutation in the
NEMO gene
Clinical features
• X-linked dominant; nearly exclusively in females
• Predilection for whites
• Usually noticed at birth
• Majority of cases sporadic, ¼ with family history in mother
• Four stages:
Vesicular: plaques studded with vesicles, bullae, and pustules in blaschkoid
arrangement, noted at birth; may be extensive, generally distributed to involve the
entire body; may recur during febrile episodes
Verrucous: warty, hyperkeratotic plaques replace blistering areas arising at
approximately 2 weeks of life
Hyperpigmented: tan-brown hyperpigmented, variably whorled streaks (Chinese
lettering) occur along a, ected Blaschko lines as verrucous stage subsides at
approximately a few months of age
Hypopigmented: lighter, cream-colored streaks develop, supplanting and
intermixing with hyperpigmented areas during infancy or childhood
• Nail, hair, dental, retinal, and ocular involvement common
• Abnormality of the CNS can cause microcephaly, mental retardation, and
Prognosis and treatment• Ophthalmologic, CNS complications can be severe
• Skin lesions may become superinfected
• Blistering stage: eosinophilic spongiosis with vacuolar degeneration, prominent
dyskeratosis, superficial perivascular eosinophil infiltrate
• Verrucous stage: verruciform epidermal hyperplasia with orthohyperkeratosis,
dyskeratosis, scattered eosinophils
• Hyperpigmented stage: superficial dermal pigment incontinence with
melanophages and overlying interface changes
• Hypopigmented stage: pigment incontinence with absence of skin appendages
• Generally not contributory (although negative direct immunofluorescence can
exclude primary immunobullous disorder)
Main differential diagnoses
• Blistering stage: infantile bullous pemphigoid, pemphigus vulgaris, erythema
toxicum neonatorum, drug hypersensitivity reaction, insect bite reaction
• Verrucous stage: epidermal nevus
• Hyperpigmented stage: postinflammatory hyperpigmentation
• Hypopigmented stage: postinflammatory hypopigmentation, hypomelanosis of ItoFig 1 Incontinentia pigmenti. Erythematous, edematous papules and plaques in a
linear distribution on the leg of a newborn. Note the scale-crust and vesicles.
Fig 2 Incontinentia pigmenti. Hyperpigmented macules with scale in a linear,
whorled pattern on the leg.
(Courtesy of J Nunley, MD; Virginia Commonwealth University, Richmond.)
Fig 3 Incontinentia pigmenti. Linear hyperpigmented whorled patches on the
lower extremity.
(Courtesy of J Nunley, MD; Virginia Commonwealth University, Richmond.)8
Fig 4 Incontinentia pigmenti. Characteristic conical teeth.
Fig 5 Incontinentia pigmenti. Focal eosinophilic spongiosis is present and
characteristic of the vesicular phase.
Fig 6 Incontinentia pigmenti. This eld shows massive hyperkeratosis,
verruciform epidermal hyperplasia, and dyskeratosis
(Courtesy of E Calonje, MD; St John’s Institute of Dermatology, London.)Pityriasis Rosea
• Generally self-limited cutaneous condition possibly associated with human
herpesviruses (HHV-7 and possibly HHV-6) characterized by finely scaling
erythematous plaques distributed in classic “Christmas tree” pattern over trunk
Clinical features
• Young adults
• No gender or racial predilection
• Seasonal: spring and autumn
• Initial erythematous scaly lesion (herald patch)
• Followed within approximately 2 weeks by fine, scaly pink erythematous papules
and plaques
• Lesions have a characteristic collarette of scale
• Arranged in a “Christmas tree” pattern along skin tension lines
• Distributed over trunk, occasionally proximal extremities
• Variably pruritic
• Atypical variants involving face and neck and distal extremities
Prognosis and treatment
• Self-limited over weeks to months
• Rarely recurs
• Treatment supportive:
• Topical corticosteroids and oral antihistamines may help alleviate pruritus
• Erythromycin and phototherapy efficacy reported
• Variable acanthosis (sometimes psoriasiform)
• Focal hyperkeratosis
• Angulated parakeratosis (tipping scale, so-called tea-pot lid sign)
• Superficial perivascular chronic inflammatory cell infiltrate
• Mild spongiosis, lymphocyte exocytosis
• Intraepidermal and perivascular erythrocytes
Immunopathology (including immunohistochemistry)
• Not contributory
Main differential diagnoses
• Guttate psoriasis
• Other subacute spongiotic dermatitides
• Adverse drug reaction
• Dermatophyte infection
• Erythema annulare centrifugum
Fig 1 Pityriasis rosea. Herald “patch” on the trunk presenting as a discrete,
fewcentimeter, oval erythematous plaque with collarette of scale.Fig 2 Pityriasis rosea. Erythematous, oval thin papules with collarette of scale in
a “Christmas tree” distribution on the trunk.
Fig 3 Pityriasis rosea. Tiny foci of parakeratosis. The epidermis is acanthotic, and
mild spongiosis is evident.9
Fig 4 Pityriasis rosea. Note the spongiosis and focal lymphocytic exocytosis. There
is a super cial perivascular lymphocytic in ltrate dermal edema and erythrocyte
Fig 5 Pityriasis rosea. Sometimes the features are subtle. There is a tiny central
focus of parakeratosis and mild acanthosis.
Fig 6 Pityriasis rosea. In this higher-power view, the mound of parakeratosis is
evident.Fig 7 Pityriasis rosea. There is mild spongiosis.Photosensitive (Phototoxic/Photoallergic)
• Group of conditions that are induced and/or exacerbated by UV light
Clinical features
• While broadly defined, photosensitivity may occur in the setting of polymorphous
light eruption, connective tissue diseases (lupus erythematosus), chronic actinic
dermatitis (including actinic reticuloid), and the porphyrias
• Phototoxic disorders:
• Not immunologically mediated
• May affect all individuals if the concentration of phototoxic substance is
• Common phototoxic agents: tar, tetracyclines, phenothiazines, psoralens,
NSAIDs, griseofulvin
• Phytophotodermatitis:
• Increased photosensitivity caused by plant-related substances
• Common causes: citrus fruits (e.g., lime oil), figs, parsnip, celery
• Photoallergic disorders:
• Affect only sensitive individuals whose immune systems are predisposed to
reaction via delayed-type hypersensitivity
• Common photoallergic agents: sunscreens, PABA, fragrances, chlorpromazine,
• More common at younger ages, with decrease in incidence past middle age
• Phototoxic dermatitis:
• Cutaneous flare can begin within minutes of sun exposure
• Tender macular erythema and edema resembling sunburn
• Blistering in severe cases
• Photoallergic dermatitis:
• Reaction occurs to agents to which the individual has been previouslysensitized and manifests typically similar to allergic contact dermatitis: pruritic
and/or tender, erythema, edema, vesiculation, and weeping that evolves into
eczematous morphology with scaling papules and plaques
• Develops lichenification over time
• Postinflammatory dyspigmentation seen
• Lesions located in photosensitive distribution: face, anterior neck, lateral arms,
upper back, exposed areas of legs and dorsal feet, with sparing of the submental
and infranasal regions
Prognosis and treatment
• Usually self-limited, but recurrent with repeat sun exposure
• Photopatch testing can help elucidate/confirm etiologies for photoallergic cases
• Key to prevention is sun protection, including covering clothing and hat,
avoidance of peak hours of sunlight, and appropriate use of sunscreen of adequate
• Acute cases may be treated with topical corticosteroids, antihistamines
• Phototoxic disorders:
• Variable hyperkeratosis
• Variable spongiosis, with occasional intraepidermal or subepidermal
• Scattered dyskeratotic cells (sunburn cells)
• Epidermal necrosis in severe cases
• Upper dermal inflammatory cell infiltrate of lymphocytes, histiocytes, and
• Melanophages may be present
• Photoallergic disorders:
• Variable acanthosis, parakeratosis, and spongiosis, sometimes with
• Superficial perivascular lymphocytic infiltrate with few eosinophils, and
scattered melanophages
Immunopathology• Not contributory
Main differential diagnoses
• Phototoxic disorders histologically may resemble chemotherapy-induced skin
• Photoallergic disorders histologically resemble allergic contact dermatitis
Fig 1 Phototoxic dermatitis. Erythema on the dorsal hand with vesicle formation
and photo-induced onycholysis.
Fig 2 Photoallergic dermatitis. Erythematous, edematous papules on the upper
arm in a photodistribution after sun exposure.Fig 3 Phototoxic dermatitis. Numerous superficial sunburn cells are present.
Fig 4 Phototoxic dermatitis. High-power view showing apoptosis, keratinocyte
vacuolation, and mild spongiosis.
Fig 5 Phototoxic dermatitis. Apoptosis and necrosis of the lower epidermis with
subepidermal vesiculation.
(Courtesy of A Lazar, MD, PhD; MD Anderson Cancer Center, Houston.)7
Fig 6 Photoallergic dermatitis. Parakeratosis, acanthosis, and an upper dermal
perivascular chronic in ammatory cell in ltrate with vascular ectasia. There is no
appreciable spongiosis.
(Courtesy of B Swick, MD; University of Iowa, Iowa City.)
Fig 7 Photoallergic dermatitis. High-power view showing a perivascular
lymphohistiocytic infiltrate with eosinophils and one or two melanophages.
(Courtesy of B Swick, MD; University of Iowa, Iowa City.)B
Psoriasiform and Pustular
• Cutaneous condition of erythematous, squamous lesions manifesting
characteristic histology
Clinical features
• Familial predisposition supported by twin studies
• Predilection for whites, fair-skin
• Equal gender
• Usually manifests in childhood
• Guttate psoriasis: antecedent strep throat
• Pustular psoriasis: may arise following systemic corticosteroid administration
• Recent research suggesting association with body habitus, nutrition, smoking,
alcohol consumption
• Certain drugs (e.g., beta-blockers, lithium) known to exacerbate condition
• AIDS associated with more severe disease
• Psoriasis vulgaris characterized by discrete, well-circumscribed erythematous
plaques with silvery scale
• Classically located on elbows, knees, scalp, sacrum, umbilicus, buttocks, perianal
• Generally symmetrically distributed
• Koebner phenomenon: development of psoriatic plaques at sites of trauma
• Auspitz sign: pinpoint bleeding at sites where the overlying scale has been peeled
• Nail involvement manifesting as pits, oil-drops, onycholysis, nail plate thickening• Several variants of psoriasis recognized:
• Guttate psoriasis: sudden appearance of drop-like lesions on the trunk and
extremities following streptococcal infection
• Inverse psoriasis: lesions develop in skin folds (axilla, perineum/groin)
• Pustular psoriasis (von Zumbusch): generalized superficial small (1- to 3-mm)
pustules, arising on background erythema, sometimes accompanied by fever,
calcium abnormalities
• Palmoplantar pustulosis: numerous 1- to 3-mm pustules arising on
erythematous palms and soles
• Acrodermatitis continua of Hallopeau: arising in childhood with disseminated
• Erythrodermic psoriasis: generalized erythema usually with diffuse scaling
(exfoliative erythroderma)
• Patients with AIDS may have extensive erythroderma, higher incidence of inverse
and palmoplantar psoriasis
• Up to 15% of patients with psoriasis can also develop psoriatic arthritis
Prognosis and treatment
• Chronic, lifelong condition with waxing-waning course punctuated by flares and
• Guttate psoriasis self-limited, following appropriate antibiotic treatment for
inciting streptococcal infection
• Pustular, erythrodermic psoriasis patients can be systemically ill
• Psoriasis in AIDS patients may be more difficult to treat
• Psoriatic arthritis should be appropriately managed
• Recent studies suggest association between psoriasis and obesity and
cardiovascular risk
• Topical therapeutic options include topical corticosteroids; topical coal tar;
topical anthralin
• Phototherapeutic options include UVB (narrowband or broadband), PUVA,
Excimer laser; chronic PUVA use associated with increased risk for skin cancer
• Systemic therapeutic options include methotrexate; cyclosporine; mycophenolate
mofetil; retinoids (acitretin); biologic agents (e.g., etanercept, infiliximab)
• Confluent parakeratosis and hypogranulosis
• Psoriasiform hyperplasia: epidermal acanthosis marked by evenly elongated rete
ridges with suprapapillary plate thinning
• Munro microabscesses: intracorneal neutrophilic collections
• Spongiform pustule of Kogoj: spongiotic intraepidermal vesicle with neutrophils
• Epidermis with scattered mitotic figures toward the basilar aspect
• Dilated and tortuous vessels within the papillary dermis
• Mild superficial perivascular lymphocytic infiltrate
• In guttate lesions, characteristic separate small mounds of parakeratosis
• Pustular lesions characterized by large spongiform pustules (macropustule)
• Not contributory
Main differential diagnoses
• Pityriasis rubra pilaris
• Seborrhoeic dermatitis
• Lichen simplex chronicus
• Inflammatory linear verrucous epidermal nevus
• Psoriasiform drug reaction
• Reiter’s syndrome (pustular variants)Fig 1 Psoriasis vulgaris. Thin erythematous plaques of psoriasis distributed over
the buttocks, a site commonly involved.
Fig 2 Psoriasis vulgaris. Close-up of a psoriatic plaque with prominent micaceous
(silver/gray) scale.
Fig 3 Inverse psoriasis. Thin erythematous plaques with slight scale in the axilla.Fig 4 Psoriasis. Pitting of the nail plate in a patient with generalized, severe
psoriasis vulgaris.
Fig 5 Psoriasis vulgaris. Scanning view showing parakeratotic scale and
acanthosis with uniform elongation of the rete ridges. Note the ridge fusion on the
right side of the field, a common feature.
Fig 6 Psoriasis vulgaris. High-power view showing neutrophils in the
parakeratotic stratum corneum. It is always prudent to exclude a fungal infection in
a specimen with features such as these.Fig 7 Psoriasis vulgaris. A typical spongiform pustule, characteristic of psoriasis.
Fig 8 Guttate psoriasis. Note the small parakeratotic mounds typical of this
(From McKee PH, Calonje E, Granter SR: Pathology of the skin, ed 3, London, 2005,
Fig 9 Pustular psoriasis. There is typical psoriasiform hyperplasia surmounted by
a macropustule.=
Fig 10 Pustular psoriasis. High-power view showing extensive spongiform
Fig 11 Pustular psoriasis. In this example, the adjacent epidermis shows
psoriasiform hyperplasia although there is no evidence of parakeratosis.
Fig 12 Pustular psoriasis. There is gross dilatation of the super cial dermal
vasculature.Reiter’s Syndrome
• Multiorgan autoimmune syndrome characterized by orogenital ulcers, arthritis,
conjunctivitis, and psoriasiform skin lesions
Clinical features
• Affects young adults
• Cases triggered by venereal infection, much more commonly males; postenteric
infectious cases show an equal gender incidence
• HLA-B27 risk factor
• Associated with HIV disease
• Infection typically of the gastrointestinal (e.g., S h i g e l l a; also S a l m o n e l l a, Y e r s i n i a)
or genitourinary (e.g., C h l a m y d i a) systems precipitates syndrome several days to
few weeks later
• Constitutional symptoms may be present
• Classic triad of arthritis, nongonococcal urethritis, and conjunctivitis
• Prostate and bladder may also be affected
• Typically arthritis of lower extremities, can have dactylitis (sausage digit),
sacroiliitis, ankylosing spondylitis
• Conjunctivitis with discharge, iritis
• “Balanitis circinata”: sharply circumscribed, shallow, painless genital ulceration
located on glans penis in uncircumcised men; keratotic papules in circumcised
men; subsequent crusting, scarring, and pain may develop; “vulvitis circinata” in
• Associated erythema of urethral meatus, or vulvovaginitis
• “Keratoderma blennorrhagicum”: erythematous vesiculopustules evolve intohyperkeratotic papules and plaques, nodules, commonly on acral surfaces (palms,
soles, penis, scalp), but also on trunk
• Onychodystrophy with nail thickening, ridging, pitting, onycholysis
• Oral ulcers usually painless
Prognosis and treatment
• Syndrome typically remits after several months, although arthritis may become
recurrent or chronic
• Uncommon cases of cardiac complications (e.g., aortic regurgitation), systemic
amyloidosis, IgA nephropathy
• Need to treat associated infection adequately with antibiotics
• Topical corticosteroids used for dermatologic findings
• For reactive arthritis, NSAIDs, sulfasalazine commonly used
• Immunosuppressive or biologic agents reserved for severe disease
• Keratoderma blenorrhagicum: parakeratosis, intracorneal macropustules,
psoriasiform hyperplasia, spongiosis, intraepidermal neutrophils, superficial
dermal chronic inflammatory cell infiltrate
• Balanitis circinata: similar to early stage of keratoderma blenorrhagicum
• Orogenital ulcers demonstrate nonspecific histology, with mixed acute and
chronic inflammation at base of shallow ulcers
Immunopathology/special stains
• Special stains help exclude primary infectious processes
Main differential diagnoses
• Psoriasis
• Behçet’s disease
• Infectious ulcers• Apthous ulcers
Fig 1 Reiter’s syndrome. Eroded erythematous macules on the glans penis. There
are several erythematous eroded papules on the mons and in the inguinal folds. The
patient also has HIV infection.
Fig 2 Reiter’s syndrome. Evolving lesion showing parakeratosis and a spongiform
Fig 3 Reiter’s syndrome. Established lesion showing massive parakeratosis andpustules within the stratum corneum.
Fig 4 Reiter’s syndrome. High-power view of underlying spongiosis and
neutrophil infiltration.
Fig 5 Reiter’s syndrome. This is a more advanced example showing a massive
Fig 6 Reiter’s syndrome. Close-up view of a micropustule.Fig 7 Reiter’s syndrome. The adjacent epidermis shows marked psoriasiform
hyperplasia.Pityriasis Rubra Pilaris
• Cutaneous papulosquamous condition presenting as salmon-colored scaling
erythema with islands of sparing, perifollicular accentuation, and distinctive scale,
and characterized histologically by alternating ortho- and parakeratosis
Clinical features
• Idiopathic disorder classified into seven types
• Classic adult type
• Atypical adult type
• Juvenile type: presents usually by 2 years of age
• Circumscribed juvenile type
• Atypical juvenile type
• HIV-associated type
• Familial form: autosomal dominant
• No racial preference
• No gender predilection
• Salmon-colored papules and plaques in generalized distribution
• Perifollicular accentuation may be prominent
• Islands of sparing characteristic
• Progresses from scalp to toes
• Palmoplantar keratoderma (PPK)
• May progress to erythroderma
• Nail changes, including discoloration and longitudinal ridging• Atypical adult type demonstrates more eczematous and/or ichthyosiform plaques
• Circumscribed juvenile type exhibits prominent follicular erythematous plaques
over knees and elbows
• Atypical juvenile type also shows acral sclerosis
• HIV-associated type additionally manifests nodules, cysts, and pustules
Prognosis and treatment
• Chronic waxing-waning course
• Persistent and lifelong in familial cases
• Remissions may be achieved in sporadic cases, particularly in classic adult type
and juvenile type
• Atypical juvenile type associated with a more chronic course
• HIV-associated type generally more refractory to conventional treatment and
seems to respond better to anti-HIV therapy
• Occasional cases associated with internal malignancy
• Therapies include topical corticosteroids, topical and systemic retinoids,
immunosuppressive agents (e.g., methotrexate, cyclosporine, azathioprine), and
new biologic agents (infliximab)
• Complications include functional impairment from PPK, homeostasis
abnormalities from erythroderma, risk of infections
• Alternating ortho- and parakeratosis in both vertical and horizontal directions
within the stratum corneum
• Perifollicular hyperkeratosis
• Psoriasiform hyperplasia with thick suprapapillary plates, broad rete ridges, and
narrow dermal papillae
• Dilated follicles with orthokeratotic plugs
• Variable, usually mild, superficial dermal chronic inflammation• Acantholysis is some cases
Immunopathology/special stains
• Not contributory
Main differential diagnoses
• Psoriasis
• Chronic spongiotic dermatitis
Fig 1 Pityriasis rubra pilaris. Pink (salmon-colored) follicular papules on the
upper thigh with minimal scale and intervening areas of normal skin (so-called
islands of sparing).
(From Brinster NK: Dermatopathology for the surgical pathologist: a pattern based
approach to the diagnosis of inflammatory skin disorders [part I], Adv Anat Pathol
15[2]:76–96, 2008.)
Fig 2 Pityriasis rubra pilaris. Plantar keratoderma.Fig 3 Pityriasis rubra pilaris. Scanning view showing psoriasiform hyperplasia
and a greatly thickened stratum corneum.
Fig 4 Pityriasis rubra pilaris. Characteristic alternating hyperkeratosis and
parakeratosis in vertical and horizontal planes.
Fig 5 Pityriasis rubra pilaris. High-power view of Figure 2.5
Fig 6 Pityriasis rubra pilaris. In contrast to psoriasis, the suprapapillary plates are
Fig 7 Pityriasis rubra pilaris. There is a lymphohistiocytic in ltrate in the
superficial dermis.
Fig 8 Pityriasis rubra pilaris. Dilated follicle with orthokeratotic plug and
perifollicular parakeratosis.Subcorneal Pustular Dermatosis
• Sterile intraepidermal pustular dermatitis manifesting as expansile plaques in
skin folds; also known as Sneddon-Wilkinson disease
Clinical features
• Rare
• Most commonly occurs in middle age, reported in children
• Female predilection
• Cause unknown
• Controversial relationship to psoriasis
• Systemic associations include:
• IgA gammopathy/multiple myeloma
• Pyoderma gangrenosum
• Also reported in rheumatoid arthritis, lupus erythematosus, inflammatory
bowel disease, thyroid disorders
• Superficial pustules on erthythematous plaque
• Annular or serpiginous morphology
• Commonly seen in skin folds: axilla, inguinal area, inframammary, abdomen
• Mild pruritus, burning sensation may be present
Prognosis and treatment
• Chronic, relapsing course
• First-line treatment: dapsone
• Alternative treatments: acitretin, phototherapy, systemic and topical steroids
• Subcorneal collections of neutrophils with rare eosinophils
• Acantholytic cells may be present
• Upper dermal neutrophils, lymphocytes
Immunopathology/special stains
• Direct immunofluorescence studies are negative
• Gram and PAS stains negative for bacteria and fungi
Main differential diagnoses
• Pustular psoriasis
• Pustular drug eruption/acute generalized exanthematous pustular dermatosis
• Bullous impetigo
• Staphylococcal scalded skin syndrome
• Pemphigus foliaceus
• IgA pemphigus
• Candidiasis, dermatophytosis
Fig 1 Subcorneal pustular dermatosis. Bright erythematous, irregular plaques on
the neck studded with dozens of fragile few-millimeter pustules or pustular
remnants.Fig 2 Subcorneal pustular dermatosis. The blister forms beneath the stratum
corneum and is neutrophil-rich.
Fig 3 Subcorneal pustular dermatosis. Note the acantholysis.Acute Generalized Exanthematous Pustulosis
• Superficial pustular hypersensitivity reaction most commonly secondary to
Clinical features
• Any age may be affected
• No gender predilection
• Most commonly occurs within the first few days to one week of beginning a new
medication: most common offending medications are beta-lactam antibiotics
(penicillin, cephalosporin, vancomycin)
• Also occurs with tetracyclines, calcium channel blockers
• Reported after viral infections
• Begins on face, axilla, inguinal areas and rapidly becomes generalized
• May be associated with fever, malaise
• Peripheral neutrophilia, eosinophilia
• Mucous membranes spared
Prognosis and treatment
• Typically resolves within 2 weeks after offending agent discontinued
• Heals with desquamation
• May treat with topical corticosteroids, antihistamines for symptomatic relief until
condition clears
Histology• Subcorneal or intraepidermal pustules
• Spongiosis
• Variable acantholysis
• Dermal edema
• Upper dermal neutrophils with admixed eosinophils and lymphocytes
• Leukocytoclastic vasculitis has also been documented
Immunopathology/special stains
• Direct immunofluorescence studies negative
• Gram and PAS stains negative for bacterial and fungal organisms, respectively
Main differential diagnoses
• Pustular psoriasis
• Subcorneal pustular dermatosis
• IgA pemphigus
• Pemphigus foliaceus
• Bullous impetigo
• Staphylococcal scalded skin syndrome
• Candidiasis, dermatophytosis
Fig 1 Acute generalized exanthematous pustulosis. Multiple small pustules within
a background of erythema.3
Fig 2 Acute generalized exanthematous pustulosis. There is hyperkeratosis and a
small intracorneal pustule. The dermis is intensely inflamed.
(Courtesy of T Brenn, MD, PhD; Western General Hospital, Edinburgh, Scotland.)
Fig 3 Acute generalized exanthematous pustulosis. The in ltrate consists of
neutrophils, lymphocytes, and histiocytes. Occasional eosinophils are present.Transient Neonatal Pustular Melanosis
• Benign vesiculopustular condition of neonates characterized by subcorneal
neutrophil pustules
Clinical features
• Usually noticed at birth
• More common in darker-skinned races
• Few to dozens of 1- to 2-mm pustules on generally noninflammatory base
• Scattered, often symmetric distribution, favoring neck and trunk
• Lesions rupture, leaving brown postinflammatory hyperpigmented macules with
superficial peeling
Prognosis and treatment
• Benign, self-limited condition
• Recurrent waves of pustules may occur for up to several weeks of life
• Some have suggested that transient neonatal pustular melanosis represents a
precocious form of erythema toxicum neonatorum
• Subcorneal neutrophil-rich pustule, eosinophils may be evident
• Mild superficial perivascular lymphocytic infiltrate
• Melanin incontinence in later stages
Immunopathology/special stains• Special stains negative for pathogenic microorganisms
Main differential diagnoses
• Bacterial impetigo
• Neonatal acne
• Infantile acropustulosis
• Toxic erythema of the neonate
• Arthropod bite reaction
Fig 1 Transient neonatal pustular melanosis. Scattered pustules on the trunk and
arm with background hyperpigmented macules and superficial peeling scale.
Fig 2 Transient neonatal pustular melanosis. There is a subcorneal pustule. The
adjacent epidermis shows mild spongiosis. Eosinophils are present in the blister
cavity and in the dermal infiltrate.Lichen Simplex Chronicus and Prurigo Nodularis
• Spectrum of cutaneous conditions representing responses to friction and rubbing
Clinical features
• Pruritic underlying dermatoses (e.g., atopic dermatitis) or generalized pruritus
without a significant primary rash (e.g., pruritus of renal disease) may serve as the
trigger for scratching, leading to lichenification or prurigo changes
• May also arise in the setting of psychiatric conditions (e.g., obsessive compulsive
• Reportedly more frequent in women
• More common in fourth to sixth decades of life
• Prurigo nodule secondary to picking
• Lichen simplex chronicus secondary to rubbing
• Thickened, keratotic, erythematous papule or nodule (prurigo nodularis) or
plaque(s) (lichen simplex chronicus)
• Accentuated skin markings
• Associated scarring
• Lesions may number from one to hundreds
• Distributed over accessible areas, particularly forearms, legs, neck, less
commonly on abdomen, upper back, genitalia; generally spares midback
• Often symmetrical
• Lesions may demonstrate superimposed crusted erosions consistent with
• Postinflammatory dyspigmentation
Prognosis and treatmentPrognosis and treatment
• Risk of superinfection
• If lesions are no longer manipulated, should heal, often with scarring or
• Treatment of underlying pruritic condition (e.g., pruritic dermatosis or
generalized pruritus associated with systemic condition) or psychiatric disorder is
• Dry skin care measures, including use of bland emollients help address possible
underlying xerosis
• Topical (or intralesional) corticosteroids or topical calcineurin inhibitors used as
antiinflammatory agents
• Sensation-altering topical agents (e.g., capsaicin, menthol, topical oatmeal
preparations) to divert attention away from impulse to scratch
• Systemic antihistamines often used
• Phototherapy may be helpful
• Mechanical barrier preparations prevent further manipulation
• Neuropsychiatric medications (e.g., tricyclic antidepressants, selective serotonin
reuptake inhibitors, gabapentin) effective for some
• Lichen simplex chronicus
• Hyperkeratosis with prominent granular cell layer
• Variable, focal parakeratosis
• Acanthosis with elongation of rete ridges
• Variable spongiosis
• Fibrosis of dermal papillae, atypical myofibroblasts sometimes seen
• Superficial perivascular mixed inflammatory cell infiltrate with eosinophils
• Prurigo nodule
• Hyperkeratosis with acanthosis
• Pseudoepitheliomatous hyperplasia sometimes present
• Variable spongiosis
• Dermal scarring1
• Mixed inflammatory cell infiltrate with eosinophils
• Prominent blood vessels (often increased in number)
• Variable peripheral nerve prominence or hyperplasia
• Rarely lymphoid follicles may be seen
• Not contributory
Main differential diagnoses
• Lichen simplex chronicus
• Psoriasis
• Chronic spongiotic dermatitis
• Prurigo nodule
• Squamous cell carcinoma
• Arthropod bite reaction
Fig 1 Prurigo nodularis. Numerous disseminated, fairly discrete, erythematous,
few-centimeter nodules and plaques with super cial erosion in a patient who
habitually picked at his legs.Fig 2 Prurigo nodularis. Somewhat linear, geometric, pink erythematous-scarred
plaque with superficial erosion; consistent with self-excoriation.
Fig 3 Lichen simplex chronicus. Hyperkeratosis, hypergranulosis and regular
psoriasiform epidermal hyperplasia are visible. Note the vertically orientated
collagen fibers in the papillary dermis, a characteristic feature.1
Fig 4 Prurigo nodularis. Scanning view showing excoriation and
pseudoepitheliomatous hyperplasia. A light lymphocytic in ltrate hugs the borders
of the epithelium. There is dermal scarring.
(Courtesy of E Calonje, MD; St John’s Institute of Dermatology, London.)
Fig 5 Prurigo nodularis. High-power view showing well-di erentiated epithelium
and a lymphocytic infiltrate.
(Courtesy of E Calonje, MD; St John’s Institute of Dermatology, London.)Inflammatory Linear Verrucous Epidermal Nevus
• Typically unilateral lesion with inflamed papules and plaques in a linear
distribution. Commonly abbreviated to ILVEN.
Clinical features
• Usually presents during infancy and childhood (but may arise in adults less
• More common in girls
• May be present at birth; usually develops in first 5 years of life
• Unilateral verrucous, erythematous plaque
• Follows the lines of Blaschko
• Often located on an extremity
• Usually pruritic
• Patients typically healthy otherwise; rare reports of associated skeletal,
neurological abnormalities
Prognosis and treatment
• Treatment for symptomatic relief: topical/intralesional corticosteroids
• Removal options for cosmetic reasons: laser therapy, surgery
• Recalcitrant to therapy
• Acanthosis and papillomatosis, with occasional neutrophils in stratum corneum
• Characteristic scale: hyperkeratosis alternates with parakeratosis• Zones of parakeratosis lack granular layer
• Zones of hyperkeratosis have expanded granular layer
• Superficial perivascular dermatitis
Immunopathology/special studies
• Not contributory
Main differential diagnoses
• Psoriasis
• Eczematous dermatitis
• Verruca
Fig 1 In5ammatory linear verrucous epidermal nevus. Discrete, erythematous
psoriasiform plaque in a linear pattern on the arm.
(Courtesy of F Awadalla, MD; Virginia Commonwealth University, Richmond.)
Fig 2 In5ammatory linear verrucous epidermal nevus. Massive increase inthickness of the stratum corneum and marked psoriasiform hyperplasia.
Fig 3 In5ammatory linear verrucous epidermal nevus. Note the alternating
parakeratosis and hyperkeratosis.C
Interface DermatitisErythema Multiforme
• Hypersensitivity reaction with characteristic targetoid skin lesions and mucosal
Clinical features
• Etiology, classic viral infection (e.g., herpes simplex, occasionally M y c o p l a s m a
infection), or, less often, drugs
• Age range from childhood to elderly; most commonly teens to 40 years old
• No clear racial predilection
• More commonly occurring in males
• Classic culprit drugs inducing erythema multiforme: antibiotics (e.g., penicillin,
sulfa-based drugs); anticonvulsants, aspirin and NSAIDs, antituberculous
• Targetoid lesions characteristic: erythematous to violaceous central slightly
raised, few-millimeter papule surrounded by thin pale rim encircled by a
fewmillimeter erythematous to violaceous outer urticarial rim resembling an iris
• Lesions may be pruritic or feel slightly “burning”
• Lesions can vesiculate
• Koebnerization (induction of lesions at sites of trauma) sometimes observed
• Occasional prodrome with fever, malaise, nausea
• May witness signs and symptoms referable to underlying associated infection
• Oral involvement characterized by plaques, erosions, and ulcerations over lips,
gums, and palate; often painful
• Ocular and genital lesions also seenPrognosis and treatment
• Generally self-limited by few to several weeks
• Occasionally may be persistent
• Supportive care
• Controversy surrounding role of corticosteroids: may help alleviate symptoms
• Variable acanthosis or epidermal atrophy
• Hyperkeratosis often present
• Vacuolar interface changes
• Spongiosis with lymphocytic exocytosis
• Apoptotic keratinocytes (cytoid bodies), can be massive resembling toxic
epidermal necrolysis
• Satellite cell necrosis
• Papillary dermal edema with vascular ectasia and endothelial swelling
• Superficial perivascular mild mixed inflammatory infiltrate including scattered
• Subepidermal clefting or blister formation and epidermal necrosis in evolved
• Classically, parakeratosis is not seen, but may sometimes be evident
• Not contributory
Main differential diagnoses
• Connective tissue disease (e.g., lupus erythematosus)
• Fixed drug eruption
• Acute graft-versus-host disease• Stevens-Johnson syndrome/toxic epidermal necrolysis
Fig 1 Erythema multiforme. Early lesions characterized by scattered
fewmillimeter erythematous macules arising on a typical site, the palm.
Fig 2 Erythema multiforme. Fully evolved palmar lesions with classic targetoid
morphology, displaying dusky erythematous central macules surrounded by white
rims of pallor, which, in turn, are encircled by thin outer erythematous peripheral
rings.Fig 3 Erythema multiforme. Early lesion showing basal cell hydropic degeneration
with cytoid bodies. There is satellite cell necrosis and a light lymphocytic infiltrate.
Fig 4 Erythema multiforme. Low-power view of another early lesion showing
hyper- and parakeratosis on the left and marked upper dermal edema on the right.
Fig 5 Erythema multiforme. High-power view of an early lesion showing
lymphocytic exocytosis and cytoid bodies.
Fig 6 Erythema multiforme. In this example, there is very extensive interfacechange.
Fig 7 Erythema multiforme. Early subepidermal vesiculation is present.
Fig 8 Erythema multiforme. This shows a more advanced example with clear
blister formation.Toxic Epidermal Necrolysis/Stevens-Johnson
• Severe hypersensitivity reaction demonstrating prominent mucocutaneous
necrosis. The term Stevens-Johnson syndrome is used when less than 30% of the
skin is affected, whereas toxic epidermal necrolysis is applied in cases where 30%
or more of skin is involved.
Clinical features
• Predominantly drug-induced
• Common culprit drugs include antibiotics (e.g., sulfa-based drugs, penicillin);
anticonvulsants (e.g., carbamazepine, phenytoin, lamotrigine); NSAIDs; and
• Usually seen in adults, although any age may be affected
• Occasional cases linked to infectious causes (e.g., Mycoplasma pneumonia)
• No clear racial predilection
• Similar condition may be seen in patients with acute graft-versus-host disease
(GVHD), although a drug-induced toxic epidermal necrolysis must be excluded
• Prominent involvement of mucosal surfaces (e.g., conjunctiva, oral mucosa,
genital mucosa) with erythematous injection, blister formation, and eroded blister
• Erythematous to grayish, often purpuric cutaneous macules (“spots”), sometimes
with targetoid morphology coalesce into diffuse dusky erythema
• Typically preceded by prodrome of skin tenderness, anxiety
• Epidermal necrosis leads to central dusky gray coloration, epidermal sloughing,
and/or blister formation
• Koebnerization (induction of lesions at sites of trauma) may be observed• Multisystem involvement possible: gastrointestinal hemorrhage, respiratory
failure, renal insufficiency
Prognosis and treatment
• Serious, potentially life-threatening condition, with mortality in greater than one
third of patients
• Complications of thermoregulation, electrolyte and fluid homeostasis impairment
• Scarring can occur in eyes and genitourinary tract
• Sepsis may lead to death
• Supportive care in a burn unit
• Controversy surrounding role of corticosteroids: may help alleviate symptoms
• Intravenous immunoglobulin use prompted by elucidation of Fas-ligand
pathophysiologic mechanism
• Thalidomide found to increase risk of death
• Judicious antibiotic therapy guided by cultures
• Severe vacuolar interface change often with subepidermal vesiculation
• Festooning (preservation of dermal papillae)
• Massive apoptosis often affecting the entire epidermis/epithelium
• Adnexal involvement, particularly sweat gland
• Satellite cell necrosis with lymphocytic exocytosis in early lesion
• Superficial perivascular mild mixed inflammatory infiltrate including scattered
• “Jelly-roll” technique for quick diagnosis: sloughed skin can be collected by
wrapping it around a cotton swab stick; frozen sections reveal full-thickness
epidermal necrosis
Immunopathology• Not contributory
Main differential diagnoses
• Erythema multiforme
• Severe acute GVHD
• Staphylococcal scalded skin syndrome
• Paraneoplastic pemphigus
Fig 1 Toxic epidermal necrolysis. Denudation and bleeding over the back of an
adult woman with toxic epidermal necrolysis suspected to be due to an
Fig 2 Toxic epidermal necrolysis. Low-power view showing a cell-freesubepidermal blister.
Fig 3 Toxic epidermal necrolysis. The blister is completely empty, dermal papillae
are preserved, and the roof is necrotic.
Fig 4 Toxic epidermal necrolysis. High-power view of the roof showing full
thickness apoptosis.
Fig 5 Toxic epidermal necrolysis. High-power view of a sweat duct with focal
apoptosis and scattered chronic inflammatory cells.Fig 6 Toxic epidermal necrolysis. High-power view of an affected hair follicle.
Fig 7 Toxic epidermal necrolysis. The adjacent nonblistered skin shows massive
apoptosis with lymphocytes tagging the interface between the epidermis and
dermis.Lupus Erythematosus
• Multisystem autoimmune condition that classically features mucocutaneous
Clinical features
• Female predilection
• Usually presents in young adulthood, in the third to fifth decades
• From dermatologic standpoint, three classic forms recognized: discoid lupus
erythematosus (DLE); subacute cutaneous lupus erythematosus (SCLE); systemic
lupus erythematosus (SLE)
• DLE:
• Photodistributed circular to oval erythematous plaques with hyperkeratotic,
adherent carpet-tack scale, telangiectasia
• Distributed commonly on the face, chest, upper trunk, and arms
• May demonstrate verrucous surface or be hypertrophic
• Scarring common
• Tumid lupus erythematosus lacks significant epidermal change
• Photodistributed eruption of psoriasiform or annular polycyclic plaques
• Commonly symmetrically distributed on the face, chest, upper trunk, and
• Photosensitivity prominent
• SLE: classically defined as the presence of 4/11 criteria:
• Malar erythema
• DLE lesions
• Photosensitivity
• Arthritis
• Serositis
• Renal involvement (e.g., nephritis)
• Oral ulcers• Hematologic abnormalities (e.g., cytopenias)
• Positive ANA
• Neurologic abnormalities (e.g., seizures)
• Other autoantibodies (e.g., anti–Smith antibody)
• SLE also commonly associated with Raynaud’s phenomenon, vasculitis, alopecia,
nail dystrophy, periungual telangiectasias/erythema
• SLE may coexist with other autoimmune diseases, such as Sjögren’s syndrome,
antiphospholipid antibody syndrome
• Neonatal LE (NLE) occurs in babies of mothers with connective tissue disease
(sometimes latent or undiagnosed), presents at birth with annular polycyclic
plaques similar to SCLE (with which it shares Ro-positivity), and is associated with
heart block; lesions on head and neck
Prognosis and treatment
• DLE complicated by scarring, risk for development of squamous cell carcinoma
and basal cell carcinoma; with generalized lesions, approximately 5% risk of
progression to SLE
• SCLE markedly photosensitive; associated risk of Sjögren’s syndrome or
rheumatoid arthritis; may eventuate into SLE in half of cases
• SLE prognosis and course dependent upon degree and nature of internal
involvement; causes of death include nephritis, infections, or CNS involvement
• NLE lesions typically regress by 6 months of age, but cardiac conduction defects
• Photoprotection is paramount to management of all forms of LE
• Antimalarials, including hydroxychloroquine, chloroquine, and quinacrine most
commonly used for treatment; topical/intralesional corticosteroids
• Other immunomodulatory agents include methotrexate, cyclophosphamide,
intravenous immunoglobulins
• DLE:
• Hyperkeratosis
• Often epidermal atrophy, occasionally irregular acanthosis• Basement membrane zone thickening
• Vacuolar interface dermatitis sometimes with cytoid bodies
• Lichenoid and superficial and deep, perivascular and periadnexal
lymphocytic inflammation
• Interstitial mucin deposition; marked in tumid variant
• Melanin pigment incontinence
• Telangiectasia
• Follicular dilatation with keratin plugging
• Hyperkeratosis, occasional parakeratosis
• Epidermal atrophy
• Vacuolar interface changes with apoptosis and satellite cell necrosis
• Lichenoid and superficial and deep, perivascular and periadnexal
lymphocytic inflammation; however, sometimes infiltrate is minimal
• Interstitial mucin deposition
• Melanin pigment incontinence
• SLE:
• Changes of DLE or SCLE depending upon clinical morphology; features are
sometimes subtle with mild interface change and epidermal atrophy only
Immunopathology/special stains
• Mucin stains highlight interstitial mucin
• Thickened basement membrane zone highlighted by PAS stain
• Direct immunofluorescence: IgG (most specific), IgM (most common), C3
immunoreactants along dermal–epidermal junction
Main differential diagnoses
• Dermatomyositis
• Mixed connective tissue disease
• Polymorphous light eruption
• B-cell lymphoma
• Jessner’s lymphocytic infiltrate
• Pseudolymphoma
• Lichen planusFig 1 Chronic cutaneous (discoid) lupus erythematosus. Discrete hypopigmented
plaques with central erythema, Bbrosis, and slight scale. The border is
(Courtesy of J Nunley, MD; Virginia Commonwealth University, Richmond.)
Fig 2 Subacute cutaneous lupus erythematosus. Annular, erythematous, scaly
papules and plaques on sun-exposed areas.Fig 3 Systemic lupus erythematosus. Young woman with malar erythema
(“butterEy rash”) and macular erythema on sun-exposed sites of chest and extensor
arms. Note dorsal hand is also involved with erythema in the interphalangeal areas
and around nail folds. This patient was anti–Ro positive.
Fig 4 Lupus vasculitis. Reticulated erythema with hyperkeratosis and multifocal
ulceration on the leg of a woman with systemic lupus erythematosus.Fig 5 Discoid lupus erythematosus. Scanning view showing hyperkeratosis and
marked follicular plugging. There is a dense perivascular and periadnexal lymphoid
Fig 6 Discoid lupus erythematosus. High-power view showing follicular
involvement. Scarring alopecia is an important complication.
Fig 7 Discoid lupus erythematosus. High-power view showing interface change.Fig 8 Discoid lupus erythematosus. Note the basement membrane thickening and
Fig 9 Subacute cutaneous lupus erythematosus. At low power, the features are
subtle. There is slight hyperkeratosis, and a perivascular chronic inEammatory cell
infiltrate is present.
(Courtesy of E Calonje, MD; St John’s Dermatology Center, London.)
Fig 10 Subacute cutaneous lupus erythematosus. Higher-power view showing
interface change.(Courtesy of E Calonje, MD; St John’s Dermatology Center, London.)
Fig 11 Subacute cutaneous lupus erythematosus. High-power view showing
numerous cytoid bodies and satellite cell necrosis.
(Courtesy of E Calonje, MD; St John’s Dermatology Center, London.)
Fig 12 Systemic lupus erythematosus. There is mild interface change. The dermis
is edematous, and there is an interstitial lymphohistiocytic inBltrate. Note the
cytoid body.Fig 13 Lupus erythematosus. Alcian blue stain highlights increased mucin in the
reticular dermis.
Fig 14 Lupus erythematosus. Diastase-PAS stain highlights a thickened basement
Fig 15 Direct immunoEuorescence. Granular IgM deposition along the basement
membrane zone.Dermatomyositis
• Autoimmune condition characterized by inflammatory myopathy and skin rash
Clinical features
• Female predilection
• Adult and juvenile forms recognized
• Erythema in a shawl-like distribution over upper chest and upper back (typically
in a photodistribution)
• Heliotrope (purplish) color over upper eyelids
• Gottron’s papules: erythematous to violaceous, thin few-millimeter papules over
interphalangeal joints and metacarpophalangeal joints of dorsal hands, may
overlie other joints
• Poikiloderma: telangiectasias, atrophy, hyperpigmentation, and
• Scalp pruritus common, alopecia
• Calcinosis, sometimes with cutaneous ulceration and extrusion through the skin,
can be present, particularly in children
• Raynaud’s phenomenon not uncommon
• Periungual erythema, splinter hemorrhages, and telangiectasia
• Proximal muscle weakness typically is present, although dermatomyositis sine
myositis can occur (skin lesions without myositis for at least 6 months)
• Raised creatine kinase, aldolase
• Overlap syndromes (e.g., dermatomyositis with scleroderma)
• Lung and heart involvement in some patients
Prognosis and treatmentPrognosis and treatment
• For patients over age 40, increased risk of internal malignancy, particularly
breast and gynecological cancers in women, typically seen within the first 2 years
of presentation
• Prednisone, other immunosuppressants (including azathioprine, methotrexate),
antimalarials, intravenous immunoglobulins
• Topical corticosteroids, photoprotection
• Hyperkeratosis and epidermal atrophy
• Loss of rete ridges
• Vacuolar interface dermatitis
• Apoptotic keratinocytes (cytoid bodies)
• Pigment incontinence
• Superficial perivascular lymphocytic infiltrate
• Mild dilatation of superficial vessels, occasional thrombotic changes
• Variable superficial dermal edema
• Dermal mucin deposition often present
• Gottron’s papules show hyperkeratosis, variable papillomatosis and acanthosis,
mild interface change
• Muscle changes include muscle necrosis and regeneration, chronic inflammatory
cell infiltrate around blood vessels and muscle fibers
Immunopathology/special stains
• Direct immunofluorescence: granular IgG and C3 along dermal–epidermal
• Blood vessel wall complement deposits (C5-C9) sometimes present
• Anti–nuclear factor often positive=
• Various nuclear antibodies; e.g., anti–Mi-2, highly specific but poor sensitivity
Main differential diagnoses
• Lupus erythematosus
• Mixed connective tissue disease
• Erythema multiforme
• Drug reaction
Fig 1 Dermatomyositis. Coalescent scaling macular and papular erythema in a
shawl-like distribution.
Fig 2 Dermatomyositis. Gottron’s pink erythematous few-millimeter at-topped
papules over the dorsal joints of the hands.Fig 3 Dermatomyositis. Periungual erythema and telangiectasia with cuticular
Fig 4 Dermatomyositis. Poikilodermatous change and alopecia on the scalp.
Fig 5 Dermatomyositis. Hyperkeratosis and an irregular epidermis. A perivascular
chronic inflammatory infiltrate is present in the superficial dermis. Note the edema.
(Courtesy of D Whittemore, DO; University of Texas, Houston.)Fig 6 Dermatomyositis. Focal liquefactive degeneration of the basal layer is
present, and there are cytoid bodies. Red cell extravasation is evident.
(Courtesy of D Whittemore, DO; University of Texas, Houston.)
Fig 7 Dermatomyositis. This field shows focal calcification in the deep dermis.Graft-Versus-Host Disease (GVHD)
• Condition of grafted transplant immune tissue reacting against host tissue,
usually in the context of bone marrow transplant, and affecting skin and other
organ systems, particularly gastrointestinal
Clinical features
• Most commonly bone marrow transplant recipient patients
• Also in recipients of certain solid organ transplants containing lymphoid tissue
(e.g., liver) and nonirradiated blood products
• Risk of developing GVHD increases with age
• Acute form presents within 100 days; chronic forms arise after 100 days
• Acute form: variably tender or pruritic, macular erythema or thin coalescent
erythematous plaques, characteristically beginning around ears, palms, soles, and
spreading centripetally to involve trunk; usually arising approximately three weeks
posttransplantation; may progress into exfoliative erythroderma, bullae
• Hyperacute form uncommon, arises within two weeks of transplant, with
associated erythroderma, fever
• Hepatitis is a common associated complication in acute form
• Enteritis, with diarrhea, abdominal pain also seen in acute form
• Chronic form lichenoid or sclerodermoid; may arise without prior acute phase
• Lichenoid chronic GVHD demonstrates coalescent, diffusely distributed thin
polygonal erythematous few-millimeter papules
• Sclerodermoid chronic GVHD demonstrates diffuse skin induration and
tightening, complicated by joint contractures
• Chronic form can be associated with ocular problems arising from lack of tear
secretion, dysphagia, and dyspneaPrognosis and treatment
• Challenging to treat effectively
• Decrease in immunosuppression may help
• Prophylactic prebone marrow transplant immunosuppressive regimens (e.g.,
cyclosporine) may help prevent GVHD
• Topical corticosteroids, cyclosporine, methotrexate, mycophenolate mofetil,
UVA1, PUVA, photophoresis, rituximab, and antithymocyte immunoglobulin all
used with variable success
• Variable hyperkeratosis, acanthosis, or epidermal atrophy (in chronic form)
• Interface inflammation with dyskeratosis (cytoid bodies) and lymphocyte
• Satellitosis describes apoptotic keratinocyte flanked by lymphocytes (but this is
not always seen)
• Subepidermal clefting can be present
• More severe form may resemble toxic epidermal necrolysis with subepidermal
• Variable spongiosis and adnexal involvement
• Eosinophils may be present
• Grover-like morphology (acantholytic dyskeratosis) may also be seen
• Lichenoid chronic GVHD shows band-like lymphocytic infiltrate with interface
changes indistinguishable from lichen planus
• Sclerodermoid chronic GVHD shows diffuse dermal sclerosis
• Melanin incontinence
• Histologic grading schemes rating degree of interface change, clefting, spongiosis,
and dyskeratosis in use
Immunopathology• GVHD mediated by donor CD3+ T cells
Main differential diagnoses
• Erythema multiforme (acute GVHD)
• Cutaneous eruption of lymphocyte recovery (acute GVHD)
• Adverse drug reaction (acute GVHD)
• Toxic epidermal necrolysis (acute GVHD)
• Connective tissue disease (acute GVHD)
• Lichen planus (lichenoid chronic GVHD)
• Scleroderma/morphea (sclerodermoid chronic GVHD)
Fig 1 Acute graft-versus-host disease. Characteristic involvement of the posterior
scalp and ear.Fig 2 Chronic graft-versus-host disease (GVHD). Posterior view of the lower legs
of sclerodermoid GVHD demonstrating skin sclerosis with areas of erythema and
Fig 3 Acute graft-versus-host disease. Scanning view showing hyperkeratosis,
epidermal atrophy, and a dense superficial dermal infiltrate.Fig 4 Acute graft-versus-host disease. There is hyperkeratosis, epidermal atrophy,
cytoid bodies, and interface change.
Fig 5 Lichenoid graft-versus-host disease. This example shows hyperkeratosis,
hypergranulosis, and irregular sawtooth acanthosis.
Fig 6 Lichenoid graft-versus-host disease. Note the interface change and cytoid
bodies.Fig 7 Sclerodermoid chronic graft-versus-host disease. There is hyperkeratosis,
hypergranulosis, and acanthosis. Note the marked dermal sclerosis.Interface Dermatitis of HIV Infection
• Interface dermatitis seen in HIV-infected individuals
Clinical features
• Occurs in the setting of HIV infection, usually advanced disease
• May be a drug reaction (e.g., to nonsteroidals and
• Develops on sun-exposed areas (e.g., face, extensor arms, neck, and chest).
• May progress to involve sun-protected sites
• Mucosal involvement typically limited to the lower lip
• Erythematous to violaceous patches and plaques
• Can be pruritic, excoriations common
• Resolves with loss of pigment in darker-skinned individuals
Prognosis and treatment
• Chronic condition
• Treatment with topical steroids
• Withdrawal of photosensitizing medications when possible
• Sun protection
• Interface alteration along the dermal–epidermal junction
• Necrotic keratinocytes, cytoid bodies, and lymphocytes at the dermal–epidermal1
• Lichenoid lymphohistiocytic infiltrate, with occasional plasma cells (but
typically, this is a cell-poor interface dermatitis)
Immunopathology/special studies
• Not contributory
Main differential diagnosis
• Other interface dermatitides including dermatomyositis, subacute lupus
erythematosus, acute graft-versus-host disease
Fig 1 Interface dermatitis of HIV infection. Erythematous, well-demarcated,
licheni ed plaques on the posterior neck in a man with HIV/AIDS. Note the marked
hypopigmentation and photodistribution.1
Fig 2 Interface dermatitis of HIV infection. Mild hyperkeratosis and
hypergranulosis. The epidermis appears attened. A band-like in ltrate is present
in the superficial dermis.
Fig 3 Interface dermatitis of HIV infection. Interface change is evident. The
infiltrate consists of lymphocytes, histiocytes, and scattered plasma cells.
Fig 4 Interface dermatitis of HIV. High-power view showing basal cell hydropic
degeneration.Fig 5 Interface dermatitis of HIV. There is marked pigment incontinence.
Fig 6 Interface dermatitis of HIV. This example is associated with a heavy
lymphocyte and plasma cell infiltrate.Pityriasis Lichenoides
• Cutaneous lymphocyte-mediated condition with two forms recognized: acute
(pityriasis lichenoides et varioliformis acuta [PLEVA]) and chronic (pityriasis
lichenoides chronica [PLC]).
Clinical features
• Acute: children, teens, young adults, with slight male predilection; no clear racial
• Chronic: adults
• Acute:
• Few to hundreds of often crusted, papulonodules, ranging from a few
millimeters to a few centimeters, distributed over the trunk and extremities
• Individual lesions evolve from vesiculation to central necrosis, followed by
scarring; variably pruritic
• Typically abrupt onset
• May have associated fever, constitutional symptoms
• Chronic:
• Fine, scaly erythematous papules to thin plaques distributed over trunk and
proximal extremities
• Occasionally pruritic
Prognosis and treatment
• Acute: benign condition; lesions may evolve into PLC; therapeutic options include
topical or systemic corticosteroids, tetracyclines, erythromycin, PUVA
• Reports of evolution into cutaneous lymphoma
• Chronic: fundamentally benign condition
• Acute:
• Acanthosis, parakeratosis often with ulceration
• Interface change
• Spongiosis, intracellular edema, lymphocytic exocytosis
• Characteristically dense, wedge-shaped, lymphohistiocytic infiltrate
occupying the superficial to deep dermis
• Dermal edema and erythrocyte extravasation
• Vasculitis may exceptionally be evident
• Chronic:
• Hyperkeratosis, parakeratosis, and mild acanthosis
• Focal interface change with apoptosis
• Mild spongiosis
• Superficial dermal lymphohistiocytic infiltrate with exocytosis
• Not contributory
Main differential diagnoses
• Arthropod bite reaction
• Mycosis fungoides
• Lymphomatoid papulosis
• Pityriasis rosea (PLC)
• Nummular eczema (PLC)
Fig 1 Pityriasis lichenoides et varioliformis acuta. Polymorphous, erythematous,edematous, variably sized papules distributed on the arm.
Fig 2 Pityriasis lichenoides chronica. Multiple erythematous papules with slight
scale on the trunk.
(From the collection of the late NP Smith, MD; the Institute of Pathology, London.)
Fig 3 Pityriasis lichenoides et varioliformis acuta. Low-power view of an evolving
lesion showing parakeratosis and intense epidermal and upper dermal
inflammation.Fig 4 Pityriasis lichenoides et varioliformis acuta. High-power view of Figure 3
showing intraepidermal edema, lymphocyte exocytosis, 7orid basal cell hydropic
degeneration, and multiple cytoid bodies.
Fig 5 Pityriasis lichenoides et varioliformis acuta. Medium-power view showing
vascular dilatation and endothelial swelling. There is a heavy lymphohistiocytic
Fig 6 Pityriasis lichenoides et varioliformis acuta. High-power view of
lymphocytes with histiocytes and one or two eosinophils.8
Fig 7 Pityriasis lichenoides chronica. Mild epidermal acanthosis with
parakeratosis and mildly dense super cial perivascular lymphocytic in ltrate with
occasional exocytosis into the epidermis.
Fig 8 Pityriasis lichenoides chronica. High-power view of Figure 7 showing focal
interface change, exocytosis, and overlying parakeratosis.
Fig 9 Pityriasis lichenoides chronica. Medium-power view showing hyperkeratosis
with focal parakeratosis, acanthosis with lymphocytic exocytosis and focal interface
change. Note the upper dermal edema and erythrocyte extravasation.D
Lichenoid DermatitisLichen Planus
• Mucocutaneous condition characterized by pruritic papules and plaques
clinically and histologically by lichenoid chronic inflammation
Clinical features
• Association with hepatitis C
• No race or gender predilection; any age can be affected
• Pruritic polygonal purple papules and plaques (5 “Ps”)
• Distribution over flexural wrists, ankles, arms, legs, trunk, genitalia, oral mucosa
• Wickham’s striae: reticulate network of lacy white scaling seen over cutaneous
papules and buccal mucosae
• Nail involvement by pterygium
• Lichenoid drug eruption similar, but generally may be photodistributed, lacks
both nail involvement, and Wickham’s striae
• Hypertrophic variant with particularly thickened, often coalescent papules and
nodules, common on lower legs
Prognosis and treatment
• Chronic waxing-waning course
• Treatment options include topical corticosteroids, systemic retinoids,
• Hyperkeratosis and irregular sawtooth acanthosis• Wedge-shaped hypergranulosis
• Basal cell hydropic degeneration and squamatization
• Lichenoid (band-like) chronic inflammatory infiltrate within the superficial
dermis lying parallel to the overlying epidermis, consisting of lymphocytes and
• Plasma cells and eosinophils generally absent
• Apoptotic (“cytoid,” “Civatte,” “colloid”) bodies
• Hypertrophic variant demonstrates particularly prominent hyperkeratosis and
Immunopathology/special stains
• Direct immunofluorescence: fibrinogen in linear or shaggy pattern along dermal–
epidermal junction; cytoid bodies may be positive for IgM
Main differential diagnoses
• Lichenoid drug eruption
• Fixed drug reaction
• Lichenoid keratosis
• Lichen striatus
• Lichenoid mycosis fungoides
• Chronic graft-versus-host disease (lichenoid)
• Squamous cell carcinoma or pseudoepitheliomatous hyperplasia can mimic
hypertrophic lichen planus7
Fig 1 Lichen planus. Polygonal, violaceous at-topped papules on the dorsal
(From the collection of the late NP Smith, MD; the Institute of Pathology, London.)
Fig 2 Lichen planus. Note the ulcer on the buccal mucosa. There are reticulated
white papules on the upper gingiva/hard palate.
Fig 3 Hypertrophic lichen planus. Violaceous, discrete plaques with thick adherent
scale on the lower leg.Fig 4 Lichen planus. There is hyperkeratosis, hypergranulosis, and irregular
Fig 5 Lichen planus. Note the basal cell hydropic degeneration.
Fig 6 Lichen planus. This field shows a subepidermal cleft filled with fibrin.7
Fig 7 Lichen planus. There are conspicuous cytoid bodies.
Fig 8 Lichen planus. Hypertrophic variant showing pseudoepitheliomatous
hyperplasia and massive hyperkeratosis.
Fig 9 Lichen planus. Direct immuno uorescence showing : brinogen in a linear
pattern along the dermal–epidermal junction.Lichenoid Drug Reaction
• Cutaneous hypersensitivity reaction to a medication manifesting with lichen
planus–like morphology; sometimes interface changes predominate
Clinical features
• Usually adults affected
• More commonly reported in women
• Common drugs implicated include angiotensin converting enzyme-inhibitors,
calcium channel blockers, beta-blockers, and thiazides; other causative drugs
reported include (although not limited to) furosemide, tetracycline, hydroxyurea,
imatinib, proton pump inhibitors, gold, allopurinol
• May or may not be photoexacerbated
• Eruption typically starts from weeks to months following administration of
• Erythematous to violaceous few-millimeter papules coalescent into larger plaques
• Often distributed over extremities, trunk
• May also be photodistributed (lichenoid photodrug)
• Variable pruritus
• Oral lesions sometimes seen
Prognosis and treatment
• Most cases self-limited with discontinuation of the culprit medication
• Topical or systemic corticosteroids, antihistamines used in some instances
• Hyperkeratosis with focal parakeratosis, irregular acanthosis
• Wedge-shaped hypergranulosis
• Basilar epidermal squamatization
• Cytoid bodies usually evident and may be seen in the upper reaches of the
• Band-like predominantly lymphocytic infiltrate within the papillary dermis
• Admixed scattered perivascular eosinophils usually identified
• Plasma cells often seen
• Melanin pigment incontinence, commonly marked
Immunopathology/special stains
• Not contributory
Main differential diagnoses
• Lichenoid keratosis
• Lichen planus
• Fixed drug eruption
• Lichenoid graft-versus-host disease3
Fig 1 Lichenoid drug reaction. Erythematous papules and plaques in a
photodistribution on the upper chest of an elderly woman taking a thiazide diuretic.
Fig 2 Lichenoid drug reaction. There is hyperkeratosis, hypergranulosis, irregular
acanthosis, and a band-like chronic in ammatory cell in ltrate indistinguishable
from lichen planus.Fig 3 Lichenoid drug reaction. Note the interface change with cytoid bodies. This
example was associated with use of a thiazide diuretic.
Fig 4 Beta-blocker drug reaction. There is hyperkeratosis, irregular acanthosis,
and a perivascular and superficial band-like inflammatory cell infiltrate.
Fig 5 Beta-blocker drug reaction. Higher-power view of Figure 4. There are
interface changes. The dermal infiltrate consists mostly of lymphocytes.Fig 6 Beta-blocker drug reaction. Note the vascular ectasia and dermal cytoid
Fig 7 Beta-blocker drug reaction. High-power view showing basal cell hydropic
degeneration.Fixed Drug Eruption
• Cutaneous reaction to a drug that recurs at the same place(s) upon repeated
exposure to that drug
Clinical features
• Adults and children affected
• No documented racial predilection
• Equal sex incidence
• Violaceous to brown, often circular or oval macule or patch a few millimeters to
several centimeters in diameter
• Triggered by exposure to long list of possible medications, commonly antibiotics
(e.g., penicillins, sulfa-based), phenolphthalein (laxative), NSAIDs,
anticonvulsants, phenothiazines
• Most common cause is trimethoprim-sulfamethoxazole
• Disseminated lesions possible
• Linear, bullous, eczematous, urticarial variants recognized
• Extremities particularly affected
• Mucosal membranes common sites
• Reexposure to medication causes recurrence of lesions, increased prominence of
old lesions
• Occasionally systemic, constitutional symptoms occur
Prognosis and treatment
• Recurrent with reexposure to drug
• Often leaves hyper- (or hypo-) pigmentation• Avoidance of the culprit drug constitutes the mainstay of treatment
• Hyperkeratosis
• Variable acanthosis
• Interface change often with numerous cytoid bodies
• Mixed dermal infiltrate of lymphocytes, histiocytes, neutrophils, and sometimes
conspicuous eosinophils
• Pigment incontinence (may be all that is seen in old lesions)
• In recurrent lesions, melanophages at deeper levels in the dermis may be seen (in
addition to more superficial findings)
Immunopathology/special stains
• Not contributory
Main differential diagnoses
• Lichen planus
• Lichenoid drug eruption
• Lichenoid keratosis
• Erythema multiforme
• Lupus erythematosus
• Graft-versus-host disease
• Erythema dyschromicum perstans (ashy dermatosis)2
Fig 1 Fixed drug eruption. Erythematous to violaceous plaque on the mandible of
a woman secondary to fluconazole. Early stage lesion.
Fig 2 Fixed drug eruption. Multiple hyperpigmented circumscribed macular
lesions. There is a slight scale. Later stage lesions.
Fig 3 Fixed drug eruption. Slight hyperkeratosis and mild acanthosis. Interface
change is evident, and there is a super cial perivascular and interstitial chronic
inflammatory cell infiltrate.Fig 4 Fixed drug eruption. High-power view showing interface change and
marked apoptosis.
Fig 5 Fixed drug eruption. Note the basal cell hydropic degeneration.
Fig 6 Fixed drug eruption. There is high level apoptosis, which may be related to
the acrosyringium. There is pigment incontinence.Fig 7 Fixed drug eruption. Scattered eosinophils, lymphocytes, and a few
neutrophils are evident.Lichen Striatus
• Papulosquamous skin condition characterized by numerous coalescent tiny
papules arranged characteristically along lines of Blaschko
Clinical features
• Most commonly seen in children, although any age may be affected
• No clear racial predilection
• Possible female predilection
• Case clustering
• Seasonal variation
• Numerous small (1- to 3-mm) skin-colored to scaly, hyperpigmented, brownish
papules coalescent into linear plaques
• Arranged along lines of Blaschko (cutaneous bands of embryologic development)
• Usually unilateral, rarely may be bilateral
• Papules are flat-topped or rough-surfaced
• Distributed over extremities, particularly the leg
• Usually asymptomatic, occasionally slightly pruritic
• Some reports suggest that these lesions may koebnerize
Prognosis and treatment
• Self-limited condition, with lesions typically resolving by 1 year
• Therapeutic options include topical corticosteroids, topical retinoids, and topical
calcineurin inhibitors
• Parakeratosis, mild acanthosis
• Spongiotic dermatitis
• Interface change with cytoid bodies
• Satellite cell necrosis
• Superficial dermal, perivascular and periadnexal lymphohistiocytic infiltrate
• Pigment incontinence
Immunopathology/special stains
• Not contributory
Main differential diagnosis
• Lichen planus
Fig 1 Lichen striatus. Erythematous scaly papules in a linear distribution on the
(Courtesy of J Nunley, MD; Virginia Commonwealth University, Richmond.)Fig 2 Lichen striatus. Obliquely cut section. There is marked hyperkeratosis with
parakeratosis, acanthosis, inflammation, and pigment incontinence.
(Courtesy of S Lyle, MD; Beth Israel Deaconess Medical Center, Boston.)
Fig 3 Lichen striatus. Note the spongiosis and lymphocytic exocytosis.
(Courtesy of S Lyle, MD; Beth Israel Deaconess Medical Center, Boston.)
Fig 4 Lichen striatus. Marked interface changes with basal cell hydropic
degeneration and conspicuous cytoid bodies.(Courtesy of S Lyle, MD; Beth Israel Deaconess Medical Center, Boston.)
Fig 5 Lichen striatus. This field highlights the massive pigment incontinence.
Fig 6 Lichen striatus. Spongiosis predominates in this area.
Fig 7 Lichen striatus. Interface change with satellite cell necrosis.Fig 8 Lichen striatus. There is a dense dermal lymphohistiocytic infiltrate.