Histopathologic Features Distinguish Alopecia Areata and Pattern Hair Loss

Histopathologic findings, identified in a study published in the Journal of Cutaneous Pathology, are useful for distinguishing alopecia areata (AA) from pattern hair loss (PHL).

In a retrospective slide review, researchers aimed to determine which histopathologic features are more useful for differentiating between AA and PHL. Scalp biopsy specimens for AA and PHL were collected from 2014 to 2019 at a tertiary referral center.

Of the 98 cases gathered, 38 were AA. Peribulbar infiltrates were identified in 63.2% of AA cases. In the AA cases, 65.5% had a catagen/telogen shift, 10.5% had lymphocytes, and 65.8% had melanin in fibrous tracts. Roughly, 84.2% had apoptotic bodies within vellus hairs, and 42.1% had small dystrophic follicles. This is compared with the PHL cases, in which 17.2% had a catagen/telogen shift, 1.7% had lymphocytes, and 8.6% had melanin in fibrous tracts. Additionally, 63.8% had apoptotic bodies within vellus hairs, and 1.7% had small dystrophic follicles.

“Common features of AA other than peribulbar infiltrates include a catagen/telogen shift, melanin in fibrous tracts, and small dystrophic follicles,” concluded the study authors. “Practitioners should consider these features when distinguishing AA from PHL in specimens without peribulbar infiltrates,” they added.

Reference
Plante J, Valdebran M, Forcucci J, et al. A comparative study of histopathologic features in alopecia areata and pattern hair loss. J Cutan Pathol. Published online ahead of print January 6, 2023. doi:10.1111/cup.14384