Lichen planopilaris: a clinicopathologic study.
Three clinicopathologic variants of lichen planopilaris are described. The first is characterized clinically by individual keratotic follicular papules and histologically by a lichenoid inflammatory cell infiltrate confined to the follicular epithelium. The second variant consists of erythematous to violaceous plaques, some of which show follicular prominence; the histologic appearance is that of a lichenoid inflammatory cell infiltrate that affects both follicular and interfollicular areas. The third variant manifests as follicular papules of the scalp with concomitant or subsequent cicatricial alopecia. In this variant the histologic hallmark is a lichenoid, follicular and interfollicular inflammation, associated with or followed by scarring. Overlap among the three variants exists, and hence the concept of a disease spectrum ranging from pure follicular involvement without evidence of clinical scarring to cicatricial alopecia of the scalp is advocated.