A comparative study of histopathologic features in alopecia areata and pattern hair loss.

Common features of AA other than peribulbar infiltrates include a catagen/telogen shift, melanin in fibrous tracts, and small dystrophic follicles. Practitioners should consider these features when distinguishing AA from PHL in specimens without peribulbar infiltrates. The retrospective design limits our ability to exclude multifactorial alopecia, such as telogen effluvium.