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

Abstract

Traction alopecia is common, but histopathologic criteria for traction alopecia have not been objectively defined. Determine whether the pauci-follicular unit (PFU) can be used as a diagnostic criterion for traction alopecia. Compared to a normal follicular unit (NFU), the PFU is a non-inflamed follicular unit with an intact sebaceous gland but fewer than 2 follicles. A retrospective review of 25 case of traction alopecia 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 traction alopecia (median 6 vs 0, p<0.001), which can be used as a helpful and easily recognizable diagnostic tool in diagnosing cases of traction alopecia. 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 traction alopecia.