Pauci-follicular unit can aid histopathologic diagnosis of traction alopecia

Key takeaways:

• Histopathologic diagnosis of traction alopecia could be done using comparisons in biopsies.
• Pauci-follicular unit counts were significantly different in traction alopecia scalps compared with normal scalps.

Pauci-follicular unit counts in alopecia biopsies can help to recognize and diagnose traction alopecia, according to a study.

“Traction alopecia has been referred to as a ‘neglected entity.’ Mechanical forces result in a biphasic process with an initial temporary stage of hair loss that with ongoing mechanical insult can progress to a permanent cicatricial alopecia,” Michelle A. Pitch, MD, and Leonard C. Sperling, MD, wrote in the Journal of the American Academy of Dermatology. “Prevention and early diagnosis, therefore, are paramount to avoid ongoing end-stage scarring alopecia.”

A retrospective review of 25 traction alopecia and 25 “normal scalp” samples was conducted using archived, de-identified slides. An expert examined each to exclude alternate or multiple diagnoses.

In those with traction alopecia vs. those with normal scalp, the total number of hairs (median, 11 vs. 29; P < .001) and total number of terminal hair follicles (6 vs. 22; P < .001) was significantly reduced; however, the researchers called the median number of vellus hairs and the median of total follicular units similar.

Further, significantly more pauci-follicular units occurred in the traction alopecia subjects compared with those with normal scalp samples (median, 6 vs. 0; P < 0.001).

“By systematically reviewing histologic parameters from traction alopecia in comparison with normal scalp, we identify a key histologic feature — the pauci-follicular unit (PFU) — as essential in the diagnosis of traction alopecia,” the authors wrote. “We show that the ratio of PFU to the total number of follicular units within a specimen in a robust quantitative tool to accurately and confidently diagnose traction alopecia.”