Temporal triangular alopecia acquired in adulthood.

Temporal triangular alopecia is a relatively common, nonscarring form of alopecia. Sometimes congenital, the vast majority of lesions appear during the first 6 years of life and remain stable thereafter. We report a case of temporal triangular alopecia arising during adulthood.

Clinical and histologic findings in temporal triangular alopecia.

BACKGROUND: Temporal triangular alopecia (TTA; also called "congenital triangular alopecia") is a common disorder that is assumed to be congenital. Little is known about its histologic features. OBJECTIVE: Our purpose was to describe four new cases, review the literature, and present histologic features based on vertical and transverse sectioning. METHODS: The history, clinical features, and histologic findings of four patients with TTA are described and the relevant literature reviewed. RESULTS: Lesions of TTA are seldom congenital, and most are best described as lancet-shaped. The "bald spot" contains normal numbers of hairs, although virtually all are vellus or indeterminate follicles. CONCLUSION: Most cases of TTA appear to develop during the first few years of life, and the designation "congenital" is a misnomer. The appearance of alopecia can be best explained as a focal zone of hair miniaturization leading to vellus hair formation.