A Comparative Cross-Sectional Study of Hair Density and Hair Shaft Diameter of Different Severities of Anterior Scalp Marginal Traction Alopecia in Women.

Introduction: Hair density (HD) studies of marginal traction alopecia (MTA) are few. We aimed to document the HD/cm², number of hair shafts (HS) per pilosebaceous unit (PU), and HS diameter of different grades of anterior scalp margin MTA (AMTA).

Methods: A cross-sectional descriptive study of 401 women over a 9-month period in 2023. The severity of AMTA was scored using the marginal traction alopecia severity score. Phototrichoscopic evaluation of HD/cm², HS diameter, and number of HS per PU was done on the alopecic intertemporal, right and left temporal, and the non-alopecic right temporal and intertemporal scalp sites.

Results: The HD/cm² of the non-alopecic intertemporal scalp site ranged from 282 to 519 cm² compared to that of the AMTA which ranged from 14 to 349/cm², p < 0.001. With increasing severity of AMTA, there was a significant decrease in HD: grade 1 had HD of 227.56/cm² compared to 131.22/cm² in grade 4 at the intertemporal area, p < 0.001. HS diameter ranged from 0.0087 to 0.0200 mm in grade 1 and 0.0078-0.0100 in grade 4. Single hair units were present in 100%.

Conclusion: Anterior scalp marginal alopecia results in a significant reduction of HD, hair shaft diameter, and number of hair strands. Preventative education on hair care practices and hair styles is advocated.