The histopathologic diagnosis of traction alopecia: An evidence-based model.

Abstract

Traction alopecia (TA) is common, but histopathologic criteria for TA have not been objectively defined. Determine whether the pauci-follicular unit (PFU) can be used as a diagnostic criterion for TA. Compared to a normal follicular unit (NFU), the PFU is a noninflamed follicular unit with an intact sebaceous gland but fewer than 2 follicles. A retrospective review of 25 cases of TA and 25 cases of "normal scalp" was performed. Data included all follicles (by size and phase), sebaceous glands, and total follicular units. Comparing data (traction vs normal), we found a significantly higher number of PFUs in cases of TA (median 6 vs 0, P < .001), which can be used as a helpful and easily recognizable diagnostic tool in diagnosing cases of TA. Comparison to other forms of alopecia was not performed. The number of PFUs in an alopecia biopsy can be used to establish the diagnosis of TA.