Porth's Essentials of Pathophysiology, 4e

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Structure and Function of the Integumentum

C h a p t e r 4 5

Circumscribed, flat, nonpalpable changes in skin color

Palpable elevated solid masses

Circumscribed superficial elevations of the skin formed by a fluid-filled cavity within the skin layers

Macule —Small, flat spot, up to 1.0 cm Examples: freckle, petechia Patch —Larger than 1.0 cm Example: vitiligo

Papule —Up to 1.0 cm Example: an elevated nevis Plaque —Elevated superficial lesion 1.0 cm or larger, often formed by coalescence of papules Nodule —Marble-like lesion larger than 0.5 cm, often deeper and firmer than papule Wheal —A somewhat irregular, relatively transient, superficial area of skin edema Examples: mosquito bite, hive

Vesicle —Up to 1.0 cm; filled with serous fluid Example: herpes simplex Bulla —1.0 cm or larger; filled with serous fluid Example: 2nd degree burns Pustule —Filled with pus Examples: acne, impetigo

FIGURE 45-8. Primary lesions may arise in previously normal skin. Authorities vary somewhat on their definition of skin lesions by size. (Adapted from Bickley LS, Szilagyi PC. Bates’ Guide to Physical Assessment and HistoryTaking. 8th ed. Philadelphia, PA: Lippincott Williams &Wilkins; 2003:103.)

Albinism, a genetic disorder in which there is com- plete or partial congenital absence of pigment in the skin, hair, and eyes, is found in all races. Although there are over 10 different types of albinism, the most common type is recessively inherited oculocutaneous albinism, in which there is a normal number of mela- nocytes but they lack tyrosinase, the enzyme needed for synthesis of melanin. It affects the skin, hair, and eyes. Individuals have pale or pink skin, white or yellow hair, and light-colored or sometimes pink eyes. Persons with albinism have ocular problems, such as extreme sensi- tivity to light and refractive problems. Treatment efforts for people with albinism are aimed at reducing their risk for skin cancer through protection from solar radiation and screening for malignant changes. Efforts to manage the vision impairment, such as glasses, preferential seat- ing in classrooms, and large-print books, are important. Vitiligo is a pigmentary problem of concern to darkly pigmented persons of all races. It may be an autoim- mune disease, a genetic defect, an excessive reactive oxygen species, a calcium imbalance, or any combina- tion of these; all are being studied. Vitiligo also affects fair-skinned persons, but not as often, and the effects usually are not as socially problematic. The classic sign of vitiligo is the sudden appearance of white patches on the skin. The lesion is a depigmented macule with definite smooth borders on the face, axillae, neck, or

extremities (Fig. 45-9). The patches vary in size from small macules to ones involving large skin surfaces. The large macular type is more common. Depigmented areas appear white, pale colored, or sometimes grayish-blue. Histologically, the depigmented areas may contain no melanocytes, greatly altered or decreased numbers of

FIGURE 45-9. Vitiligo with various shades of hypopig­ mentation, depigmentation, and islands of spontaneous repigmentation. (From Goodheart HP. Goodheart’s Photoguide to Common Skin Disorders. 3rd ed. Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams &Wilkins; 2008:275.)