THE ENCYCLOPEDIA OF SKIN AND SKIN DISORDERS THE ENCYCLOPEDIA OF SKIN AND SKIN DISORDERS Third Edition Carol Turkington Jeffrey S. Dover, M.D. Medical Illustrations Birck Cox To the memory of Dottie Kennedy, for her unfailing support h The Encyclopedia of Skin and Skin Disorders, Third Edition Copyright © 1996, 2002, 2007 by Carol Turkington All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Facts On File, Inc. An imprint of Infobase Publishing 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Turkington, Carol. The encyclopedia of skin and skin disorders / Carol Turkington, Jeffrey S. Dover ; medical illustrations, Birck Cox.— 3rd ed. p. cm. Includes index. ISBN 0-8160-6403-2 1. Dermatology—Encyclopedias. 2. Skin—Diseases—Encyclopedias. 3. Skin—Encyclopedias. I. Dover, Jeffrey S. II. Title. RL41.T87 2006 616.5003—dc22 2005057402 Facts On File books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755. You can fi nd Facts On File on the World Wide Web at http://www.factsonfi le.com Text and cover design by Cathy Rincon Printed in the United States of America VB FOF 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper. CONTENTS Foreword vii Introduction xv Acknowledgments xvii Entries A–Z 1 Appendixes 405 Glossary 425 Bibliography 429 Index 439 FOREWORD The future of skin disease prevention and treat- longed, lasting months to years after a 20-week ment is bright. Better understanding of the course, a result unable to be achieved by any genetics of disease will help researchers to dis- other acne medication. Some side effects from cover the causes of many common ailments, isotretinoin are seen in most of its users, but usu- and continued technological developments ally resolve one to three weeks after treatment. will ensure even better treatments. The major These include dryness of the skin, mouth, and advances in dermatology over the last decade membranes, as well as chapped lips and patches include revolutionary anti-acne medication and of eczema. Fragile skin and susceptibility to sun- drugs that combat immune diseases; advances burn are frequently reported. Dry eyes, nose- in skin cancer awareness; new lasers and light bleeds, hair shedding, muscle and joint pains are sources engineered to improve skin appearance, common. Bone and blood lipid abnormalities can texture, and tone; and the development of Botu- also occur. Recently, depression and suicide have linum Exotoxin A and fi llers to decrease facial been reported among patients taking isotretinoin, lines and creases. although in the past some studies had shown an The single most notable event in the fi eld improvement in emotional well-being. Whether of acne treatment was the crucial discovery of isotretinoin plays a role in depression is unclear. isotretinoin in 1979 for the treatment of severe A recent large study failed to show an increased acne. This drug’s approval in 1982 revolution- risk of depression in isotretinoin users compared ized therapy; today the drug remains the treat- with other acne patients. ment of choice for resistant severe nodular cystic One of the most signifi cant problems with acne, although it is under increasing regulatory isotretinoin is its risk of the development of serious scrutiny because of uncommon but potentially birth defects in the infants of women who conceive signifi cant side effects of birth defects and depres- while on treatment. This requires that no woman sion. Isotretinoin belongs to a class of compounds being put on the drug become pregnant under any called retinoids, which are vitamin A derivatives. circumstances. To prevent pregnancy in women It is the only truly effective treatment against undergoing isotretinoin treatment, contraceptive severe cystic acne and has been shown to pre- counseling prior to starting treatment is essential, vent scarring, a disastrous result of acne. Isotreti- and strict monitoring of women of childbearing noin affects the sebaceous gland, suppressing age during the treatment course is performed. Two sebum production to preteen levels and causes negative pregnancy tests are required prior to the a decrease in the levels of bacteria responsible start of therapy, and monthly testing is compul- for acne. It also promotes shedding of skin cells. sory for sexually active females during treatment. Isotretinoin can reduce acne by 90 percent or Guidelines suggest that pregnancy is safe one more within three months. Its effects are pro- month after stopping the drug. vii viii Foreword Immunologic Drugs in an effort to reduce the risk of overuse of these highly effective treatments. IFN-a Interferon alpha is an agent that can modulate the immune system used in the treat- ment of cancers of the blood, immune diseases, Systemic Biologics and in the treatment of genital warts. A large Recent advances in technology have led to a pro- number of new clinical uses of interferon are being liferation of new strategies for treating diseases developed. The recent introduction of interferon with agents that can be designed to act specifi cally alpha into current therapies for malignant mela- on the immune system and may prove to be safer noma is notable. As immune control mechanisms than traditional therapies. Biologic agents are seem to be important in the behavior of mela- proteins that can be extracted from animal tissue noma, biological agents have been the subject of or synthesized in the laboratory. These medica- many studies involving treatment. Results sug- tions are divided into two categories: monoclonal gest that interferon alpha may be benefi cial, most antibodies and fusion receptor proteins. Mono- clearly in preventing recurrence but also perhaps clonal antibodies are usually derived from mouse in overall survival. Further studies are needed in antibodies and engineered to be better tolerated order to determine its benefi t, and it cannot yet by human beings. Fusion receptor proteins are be recommended as a standard therapy in high- human antibodies that are constructed in the risk malignant melanoma, although it remains a laboratory from components that are not normally promising mode of treatment. combined by the human body. Over the last decade, immune mediated diseases Topical Immunomodulators Imiquimod cream such as Crohn’s disease and rheumatoid arthri- induces the release of interferons and has been tis have been successfully treated with biologic approved in the United States for the treatment of agents. In 2003 the Food and Drug Administra- genital warts, as well as actinic keratoses (pre–skin tion (FDA) approved alefacept, a fusion receptor cancers). Research also shows that it is effective protein, for the treatment of moderate to severe in the treatment of superfi cial spreading basal psoriasis. This drug reduces the number and func- cell carcinoma, a slowly growing local type of tion of specifi c white blood cells important in skin cancer; studies are currently under way that infl ammatory reactions of the skin. Efulizumab, examine its effectiveness in the treatment of pre- an example of a monoclonal antibody, similarly cancerous skin growths due to the sun, nongenital decreases the ability of white blood cells to par- warts, molluscum, and alopecia areata. ticipate in infl ammation. Etanercept, a fusion Tacrolimus ointment (Protopic) and pimecro- receptor protein, binds the infl ammatory molecule limus cream (Elidel) are powerful topical anti- tumor necrosis factor-alpha (TNF-a). The reduc- infl ammatory agents approved for the treatment tion of TNF-a leads to the improvement of many of eczema. The greatest development in the treat- infl ammatory disorders of the skin. ment of eczema since the discovery of steroids in These three drugs have been approved for the the 1950s, its major advantage over topical cor- treatment of moderate to severe psoriasis. Other ticosteroids, the mainstay of treatment of atopic biologics, such as adalimumab and infl iximab, dermatitis treatment, is that it is not associated have been used to successfully treat psoriasis, with the development of the side effects such as though they are not approved by the FDA for this thinning of the skin and the formation of promi- use. Many of these biologics have demonstrated nent blood vessels and stretch marks. These new the ability to improve other infl ammatory dis- agents are particularly useful at sites where the eases of the skin such as hidradenitis suppurativa skin is more delicate, such as the face, groin, and and pyoderma gangrenosum. These agents and underarms. They should be used only on the their effectiveness in treating other diseases will affected area until it clears and then treatment remain an area of intense investigation in the should be discontinued until the next outbreak future. Foreword ix Systemic biologics are an exciting new option Advantages of pulse therapy include effective- in the management of some skin diseases. These ness with a similar or decreased frequency of side drugs are signifi cantly more expensive than tradi- effects, economy, and convenience. tional systemic medications such as methotrexate and acitretin, though they may prove to be safer UVB narrow band for chronic use. Long-term evaluation of the cost effectiveness and safety of these new medications Among the most effective therapies for psoria- will determine their ultimate role in dermatology. sis is ultraviolet light phototherapy at 290–320 nm wavelength, and more recently narrowband UVB at 311 nanometers wavelength, which has Antifungals been shown to be more effective than broadband Today most cases of nail fungus can be cured using UVB.