ABC of Dermatology
ABC of Dermatology
The clinical features of skin lesions are related to the underlying pathological processes.
Broadly skin conditions fall into three clinical groups: (a) those with a well-defined appearance and distribution; (b) those with a characteristic pattern but with a variety of underlying clinical conditions; (c) those with a variable presentation and no constant association with underlying conditions.
Skin lesions may be the presenting feature of serious systemic disease, and a significant proportion of skin conditions threaten the health, the well-being and even the life of the patient.
Descriptive terms such as macule, papule, nodule, plaque, induration, atrophy, bulla and erythema are defined and illustrated.
The significance of morphology and distribution of skin lesions in different clinical conditions are discussed. Introduction
The aim of this book is to provide an insight for the non-dermatologist into the pathological processes, diagnosis and management of skin conditions. Dermatology is a broad specialty with over 2000 different skin diseases, the most common of which are introduced here. Pattern recognition is often the key to successful history-taking and examination of the skin, usually without the need for complex investigations. Although dermatology is a clinically orientated subject an understanding of the cellular changes underlying the skin disease can give helpful insights into the pathological processes. This understanding aids the interpretation of clinical signs and overall management of cutaneous disease. Skin biopsies can be a useful adjuvant to reaching a diagnosis; however, clinicopathological correlation is essential in order that interpretation of the clinical and pathological patterns is put into the context of the patient.
The interpretation of clinical signs on the skin in the context of underlying pathological processes is a theme running through the chapters. This helps the reader to develop a deeper understanding of the subject and should form some guiding principles that can be used as tools to help assess almost any skin eruption.
Clinically cutaneous disorders fall into three main groups.
1 Those that generally present with a characteristic distribution and morphology that leads to a specific diagnosis - such as chronic plaque psoriasis ( Figure 1.1 ) and atopic eczema. 2 A characteristic pattern of skin lesions with variable underlying causes - such as erythema nodosum and erythema multiforme. 3 Skin rashes that can be variable in their presentation and/or underlying causes - such as lichen planus and urticaria.
A holistic approach in dermatology is essential as cutaneous eruptions may be the first indicator of an underlying internal disease. Patients may, for example, first present with a photosensitive rash on the face, but deeper probing may reveal symptoms of joint pains etc. leading to the diagnosis of systemic lupus erythematosus ( Figure 1.2 ). Similarly a patient with underlying coeliac disease may first present with blistering on the elbows (dermatitis herpetiformis). It is therefore important not only to take a thorough history ( Box 1.1 ) of the skin complaint but in addition to ask about any other symptoms the patient may have, and examine the entire patient carefully.
Figure 1.1 Extensive psoriasis.
Figure 1.2 Lupus erythematosus.
Box 1.1 Dermatology history-taking
Where? Site of initial lesion(s) and subsequent distribution
How long? Continuous or intermittent?
Trend? Better or worse?
Previous episodes? Timing? Similar/dissimilar? Other skin conditions?
Who else? Fami