Temporal triangular alopecia with decreased follicular density.

Temporal triangular alopecia (TTA) is a type of alopecia that is often congenital, and clinically exhibits hair loss on one or both temples. It is characterized histologically by a normal number of small hair follicles without significant inflammation. We report a patient with TTA whose biopsy exhibited a decreased number of hair follicles. There are limited reports of the histopathology of TTA, and most have utilized standard vertical sections. Of the handful of patients with transversely sectioned biopsies, follicular numbers have been reportedly normal. Our finding of a patient with TTA with a decreased number of hair follicles broadens the histologic spectrum of this disorder, and may have implications for pathogenesis.