A histologic review of 27 patients with lichen planopilaris.

Abstract

Lichen planopilaris (LPP) is a potential trichologic emergency that can result in permanent scarring alopecia. Histopathology is a key component of the diagnostic work-up. To identify the key histologic features that characterize LPP in order to facilitate diagnosis, ultimately leading to improved patient outcomes. Scalp biopsy specimens from 27 confirmed cases of LPP were reviewed in a blinded fashion to determine diagnostically helpful histologic features. Absence of arrector pili muscles and sebaceous glands, a perivascular and perifollicular lymphocytic infiltrate in the reticular dermis and mucinous perifollicular fibroplasia within the upper dermis with absence of interfollicular mucin, and superficial perifollicular wedge-shaped scarring were characterizing features. Sample size was limited, given that biopsy specimens were taken from lesions at varying stages of evolution and findings vary with disease stage. This study confirms many previously reported histologic features and highlights new characterizing features of mucinous perifollicular fibroplasia.