Hair counts from normal scalp biopsy in Taiwan

Background: Horizontal scalp biopsy is a better method to use when evaluating hair disorders, but an accurate diagnosis requires quantitative data regarding normal hair counts to be used as a control, which are currently available only for Caucasians, African Americans, Koreans, and Iranians. Objectives To evaluate scalp hair counts in the Taiwanese population. Methods Two 4-mm punch biopsies were taken from clinically normal-looking scalp skin of 31 patients who underwent scalp surgery for non-hair-loss disorders. Punch biopsy specimens were sectioned horizontally at the sebaceous gland level and the number of follicular units, terminal hairs including anagen and telogen hairs, and vellus hairs were counted and compared with other published data. The numbers of hairs were also compared between the sexes, different age groups, and different anatomical locations of the scalp. Results: The average counts of total hairs, terminal hairs, vellus hairs, and follicular units per 4-mm punch scalp skin were 21.3, 20.5, 0.8, and 9.4, respectively. The mean ratio of anagen hair to telogen hair was 91.6:8.4 and of terminal hair to vellus hair was 25.3:1. The average density of hair follicles was 1.69 mm². The mean counts of terminal hairs, total hairs, follicular units, and hair follicles/mm² were significantly different between different age groups. Conclusion Differences in hair count parameters were recognized between different ethnic groups. Parameters of hair density established in the Taiwanese population will provide clinicians with useful reference data for the evaluation of hair disorders in Asians.