Differential Diagnosis in Dermatology

Richard Ashton, Barbara Leppard

• Publisher: CRC Press
• Year: 2021
• Print ISBN:
  9780367085971
  9780367085988
• eBook ISBN:
  9780429662867
• Edition: 5
• Topic: Medicine
• Subtopic: Dermatology

DIFFERENTIAL DIAGNOSIS IN DERMATOLOGY

Fifth Edition

RICHARD ASHTON, MA, MD, FRCP, Consultant Dermatologist, Lighthouse Clinic, Isle of Wight, UK, formerly Consultant Dermatologist to the Royal Navy

BARBARA LEPPARD, DM, FRCP, Retired Consultant Dermatologist, Southampton University NHS Trust, UK

The ethos of this bestselling text is that however much or little you know about skin disease you can always arrive at the right diagnosis. The secret is to examine the surface of the rash or skin lesion which will help you classify the clinical features correctly - colour, surface features, type of lesion, border and how long it has been present. Algorithms throughout each chapter give the differential diagnosis for the features you have elicited. Accompanying clinical photographs and clear descriptions of the conditions will enable you to check whether you are right or not. If your choice seems unlikely, any conditions that could be confused with the one you selected are listed along the base of the algorithm to help you compare diagnoses so that you can get to the right answer.

We hope this new edition - enhanced with specific instructions on treatment - will be the only quick clinical reference you will ever need for dermatology diagnoses.

With over 1000 illustrations.

1

Introduction to dermatological diagnosis

DIAGNOSIS OF SKIN DISEASE

The diagnosis of skin disease is made by following the same general principles as in any other branch of medicine. Begin by taking a history. This is followed by careful physical examination. If at this stage the diagnosis has not been made, further investigations can be carried out. It is very easy to look at a rash or skin lesion and ‘guess’ the diagnosis. This is quite unnecessary. In this chapter, we give you the tools you will need to enable you to make the correct diagnosis.

HISTORY OF PRESENTING COMPLAINT

Duration of individual lesions

How long have the lesion(s) been present? This is the most important question in the history. Acute lesions present for less than 2 weeks need to be distinguished from chronic ones.

Do the lesions come and go? Do they occur at the same site or at different sites? This question is particularly important if the diagnosis of urticaria or herpes simplex is being considered. Urticaria (p. 125) can be diagnosed by a history of lesions coming and going within a 24 hour period. To establish the transitory nature of urticarial weals, draw a line around a weal and ask the patient to return the next day. You will see that the site and shape will have changed. Herpes simplex (p. 77) and fixed drug eruptions (p. 133) last around 7–14 days and usually reoccur at the same site.

Relationship to physical agents

A past history of living or working in a hot climate may be the clue you need for the diagnosis of skin cancer. Determine the patient's skin response to sun exposure. Six skin types are recognised depending how well a patient develops a skin tan.

Table 1.01 Skin types

Type 1: Always burns, never tans Type 2: Always burns, tans minimally Type 3: Sometimes burns, tans gradually Type 4: Rarely burns, tans well Type 5: Asian skin Type 6: Black skin Those with fair skin (types 1 and 2) are more liable to develop skin cancers.

In rashes on the face and backs of the hands, ask about relationship to sun exposure. The important questions to ask are the time interval after sun exposure before the rash occurs and whether the patient gets the rash through window glass on a sunny day. In solar urticaria‚ the rash occurs within 5 minutes of sun exposure and is gone in an hour. In polymorphic light eruption (p. 71)‚ the rash occurs several hours after sun exposure and lasts several days. In porphyria (which is very rare, p. 301), the rash occurs within a few minutes and lasts several days. Rashes that occur through window glass are due to UVA and will need a sunblock containing titanium dioxide or zinc oxide (see p. 27).

Ask about irritants on the skin in hand eczema (p. 305), e.g. detergents and oils and about working practices and hobbies. Are the hands protected by rubber gloves or in direct contact with irritants?

Itching

Itching is a nuisance to the patient but may not help you in making a diagnosis. Severe itching especially at night bad enough to prevent sleep should make you think ...

Table of contents

• Cover
• How to use this book
• Dedication
• Title Page
• Copyright Page
• Contents
• 1 Introduction to dermatological diagnosis
• 2 Introduction to dermatological treatment
• 3 Hair and hairy scalp
• 4 Acute erythematous rash on the face
• 5 Chronic erythematous rash on the face
• 6 Mouth, tongue, lips and ears
• 7 Acute erythematous rash on the trunk and limbs
• 8 Chronic erythematous rash and lesions on trunk and limbs
• 9 Non-erythematous lesions
• 10 Flexures
• 11 Genitalia
• 12 Lower legs
• 13 Hands & feet
• 14 Nails
• General index
• List of drugs and associated drug reactions
• Classification of topical steroids by potency
• Emollient products – how and when to use
• Wash products
• Bath emollients
• Summary of types of wound and dressing to use
• Debriding agents
• Reducing bacterial counts and odour
• Absorption of exudate
• Wound and ulcer dressings
• Index of algorithms