Diagnosing the common alopecias.

Ample scalp biopsies, including subcutaneous fat, are easily obtained by excision or punch biopsy. Using a knowledge of normal hair patterns and histologic features, the physician can identify common baldness, trichotillomania, alopecia areata, discoid lupus erythematosus, lichen planopilaris, tinea capitis and follicular mucinosis. While hair loss is usually of more psychologic than physiologic significance, accurate diagnosis can be of great importance.