What are the important elements of a skin examination of a patient with a pigmentation disorder?

The entire skin surface should be evaluated with attention to the color, shape, and distribution of the lesion(s). Lesion color helps to place the disorder into a specific category to aid in narrowing the diagnostic possibilities. The shape of a lesion is sometimes diagnostic. Linear areas of depigmentation, often in areas of trauma, are suggestive for vitiligo, whereas ash-leaf–shaped hypopigmented macules suggest tuberous sclerosis. Distribution of pigmentary changes also helps in diagnosis. Symmetrical depigmentation on the arms, legs, and/or torso suggests vitiligo. Increased pigmentation of the oral mucosa, axillae, and palmar creases is associated with Addison’s disease.

Other diagnostic tests: Wood’s lamp examination is sometimes helpful. Skin biopsy, with or without special stains for melanin (silver nitrate or the Fontana-Masson stain), determines epidermal melanocyte number and the extent and location of epidermal and dermal pigmentation.