Walter H. C. Burgdorf

Disorders of Pigmentation

Skin color can be categorized according to whether it is hypopigmented (lighter than normal skin) or hyperpigmented (darker than normal skin). Pigmentation can be melanin- related or not melanin-related. We consider here only color changes; pigmented tumors, both benign and malignant, are considered in Chapters 20 and 21.

Atopic Dermatitis and Other Dermatitides

There are several unrelated diseases which clinically present as dermatitis with redness, crusting, scaling, and weeping. Their causes are even less clear than the causes of the allergic dermatitides, discussed in the preceding chapter.

Connective Tissue Disorders

Several diseases characterized by involvement of the connective tissue lead to arthritis and the dermal changes of atrophy and sclerosis. The same diseases often have serologic evidence of circulating antibodies directed against normal cell components. For this reason they are also called autoimmune diseases.

Seborrheic Dermatitis and Acne

Sebum is the oily secretion of the sebaceous glands. If secretion is excessive, it helps make the skin oily, as in many teenagers; if the proper amount is secreted, it simply keeps the skin lubricated. Fig. 14-1 shows the normal physiology of sebum production, and Fig. 14-2 shows how certain external factors may influence it. Actually, sebum provides only part of the surface lipids, as Fig. 14-3 illustrates.

Granulomatous Infections and Other Granulomas

Many skin diseases show granuloma formation with epithelioid and giant cells (Fig. 6-1). Although tuberculosis is the prototype of such inflammation, many seemingly unrelated diseases produce a similar histologic picture (Fig. 6-2).

Dermatology and Internal Disease

Cutaneous findings frequently aid in the diagnosis of systemic disease. In this chapter, we discuss a variety of metabolic disorders with fairly distinct cutaneous changes, as well as review cutaneous markers for internal malignancy.