Chapter 15 The skin, nails, and lumps
The dermatological history
With any rash or skin condition, it is important to determine when and where it began, its distribution, whether it has changed over time, its relationship to sun exposure or heat or cold, and any response to treatment1 (see Questions box 15.1). Ask if pruritus is associated; localised pruritus is usually due to dermatological disease. Determine if pain or disturbed sensation has occurred; for example, inflammation and oedema can produce pain in the skin, while disease involving neurovascular bundles or nerves can produce anaesthesia (e.g. leprosy, syphilis). Constitutional symptoms such as fever, headache, fatigue, anorexia and weight loss also need to be documented.
Questions box 15.1
A detailed social history needs to be obtained regarding occupation and hobbies, as chemical exposure and contact with animals or plants can all induce dermatitis. All medications that have been taken must be documented. Orally ingested or parenteral medications can cause a whole host of cutaneous lesions and can mimic many skin diseases (Table 15.1). Similarly, a family history of atopic dermatitis, hay fever or skin infestation can be helpful.
1 Acne, e.g. steroids |
2 Hair loss (alopecia), e.g. cancer chemotherapy |
3 Pigment alterations: hypomelanosis (e.g. hydroxyquinone, chloroquine, topical steroids), hypermelanosis (page 449) |
4 Exfoliative dermatitis or erythroderma (page 448) |
5 Urticaria (hives), e.g. non-steroidal anti-inflammatory drugs, radiographic dyes, penicillin |
6 Maculopapular (morbilliform) eruptions, e.g. ampicillin, allopurinol |
7 Photosensitive eruptions, e.g. sulfonamides, sulfonylureas, chlorothiazides, phenothiazines, tetracycline, nalidixic acid, anticonvulsants |
8 Drug-induced lupus erythematosus, e.g. procainamide, hydralazine |
9 Vasculitis, e.g. propylthiouracil, allopurinol, thiazides, penicillin, phenytoin |
10 Skin necrosis, e.g. warfarin |
11 Drug-precipitated porphyria, e.g. alcohol, barbiturates, sulfonamides, contraceptive pill |
12 Lichenoid eruptions, e.g. gold, antimalarials, beta-blockers |
13 Fixed drug eruption, e.g. sulfonamides, tetracycline, phenylbutazone |
14 Bullous eruptions, e.g. frusemide, nalidixic acid, penicillamine, clonidine |
15 Erythema nodosum or erythema multiforme (page 448) |
16 Toxic epidermal necrolysis, e.g. allopurinol, phenytoin, sulfonamides, non-steroidal anti-inflammatory drugs |
17 Pruritus (page 445) |
Examination anatomy
Figure 15.1 shows the three main layers of the skin—epidermis, dermis and subcutaneous fat. These layers can all be involved in skin diseases in varying combinations. For example, most skin tumours arise in the epidermis (Figure 15.2a&b), some bullous eruptions occur at the epidermo-dermal junction, and lipomas are tumours of subcutaneous fat. The skin appendages which include the sweat (eccrine and apocrine) glands, hair follicles (Figure 15.3) and the nails are common sites of infection.
The nails are formed from heavily keratinised cells that grow from the nail matrix. The matrix grows in a semilunar shape and appears as the lunules in normal finger and toe nails. Hair is also the product of specialised epithelial cells and grows from the hair matrix within the hair follicle.
General principles of physical examination of the skin
The aim of this chapter is to provide an approach to the diagnosis of skin diseases.2,3 Particular emphasis will be placed on cutaneous signs as indications of systemic disease. Other chapters have included the usual clues that can be used to arrive at a particular diagnosis. This chapter tries to unify the concept of ‘inspection’ as a valuable starting point in the examination of the patient.
Ask the patient to undress. The whole surface of the skin and its appendages should be carefully inspected (Table 15.2).
1 Hair |
2 Nails |
3 Sebaceous glands—oil-producing and present on the head, neck and back |
4 Eccrine glands—sweat-producing and present all over the body |
5 Apocrine glands—sweat-producing and present in the axillae and groin |
6 Mucosa |
When one is examining actual skin lesions, a number of features should be documented. First, each lesion should be described precisely, including colour and shape. Use the appropriate dermatological terminology (Table 15.3), even though this may seem to make dermatological diseases more, rather than less, mysterious. As many dermatological diagnoses are purely descriptive, a good description will often be of considerable help in making the diagnosis. Second, the distribution of the lesions should be noted, as certain distributions suggest specific diagnoses. Third, the pattern of the lesions—such as linear, annular (ring-shaped), reticulated (net-like), serpiginous (snake-like) or grouped—also helps establish the diagnosis. Then palpate the lesions, noting consistency, tenderness, temperature, depth and mobility. Types of skin lesions are shown in Figure 15.4 and a clinical algorithm for diagnosis is presented in Figure 15.5.
Figure 15.4 Types of skin lesions
(a) Primary skin lesions, palpable with solid mass.
(b) Primary skin lesions, palpable and fluid-filled.
(c) Special primary skin lesions.
(d) Secondary skin lesions, below the skin plane.
(e) Secondary skin lesions, above the skin plane.
Adapted from Schwartz M. Textbook of physical diagnosis, 4th edn. Philadelphia: Saunders, 2002.
How to approach the clinical diagnosis of a lump
First, determine the lump’s site, size, shape, consistency and tenderness. Next, evaluate in what tissue layer the lump is situated. If it is in the skin (e.g. sebaceous cyst, epidermoid cyst, papilloma), it should move when the skin is moved, but if it is in the subcutaneous tissue (e.g. neurofibroma, lipoma), the skin can be moved over the lump. If it is in the muscle or tendon (e.g. tumour), then contraction of the muscle or tendon will limit the lump’s mobility. If it is in a nerve, pressing on the lump may result in pins and needles being felt in the distribution of the nerve, and the lump cannot be moved in the longitudinal axis but can be moved in the transverse axis. If it is in bone, the lump will be immobile.
Place a small torch behind the lump to determine whether it can be transilluminated.
Note any associated signs of inflammation (i.e. heat, redness, tenderness and swellinga).
Look for similar lumps elsewhere, such as multiple subcutaneous swellings from neurofibromas or lipomas. Neurofibromas are smaller than lipomas. They look hard but are remarkably soft; they occur in neurofibromatosis Type 1 (von Recklinghausen’sb disease). They continue to increase in number throughout life and are associated with café-au-lait spots and sometimes spinal neurofibromas.
Correlation of physical signs and skin disease
There are many different skin diseases with varied physical signs. With each major sign the groups of common important diseases that should be considered will be listed.
Pruritus
To determine the cause of the pruritus it is essential to examine the skin in detail (Table 15.4). Excoriations are caused by scratching, regardless of the underlying cause. Specific features of cutaneous diseases such as dermatitis, scabies (Figure 15.6) or the blisters of dermatitis herpetiformis should be looked for.
1 Asteatosis (dry skin) |
2 Atopic dermatitis (erythematous, oedematous papular patches on head, neck, flexural surfaces) |
3 Urticaria |
4 Scabies |
5 Dermatitis herpetiformis |
When primary skin diseases have been excluded, a detailed history and examination should be undertaken to consider the various systemic diseases listed in Table 15.5.
1 Cholestasis, e.g. primary biliary cirrhosis |
2 Chronic renal failure |
3 Pregnancy |
4 Lymphoma and other internal malignancies |
5 Iron deficiency, polycythaemia rubra vera |
6 Endocrine diseases, e.g. diabetes mellitus, hypothyroidism, hyperthyroidism, carcinoid syndrome |
Erythrosquamous eruptions
Asymptomatic lesions on the palms and soles are suggestive of secondary syphilis, whereas itchy lesions in the same location would be more suggestive of lichen planus (Figures 15.7 and 15.8). Lichen planus is occasionally associated with primary biliary cirrhosis and other liver diseases, chronic graft-versus-host disease and drugs (e.g. gold, penicillamine). Scattered lesions of recent origin on the trunk would be more suggestive of pityriasis rosea (Figure 15.9), whereas more widespread, diffuse and intensely itchy lesions would be more suggestive of nummular eczema (Figure 15.10) (Table 15.6).