Material and Method: Twenty autopsy patients of clinically normal scalp were obtained for study from the Department of Forensic Medicine, Siriraj Hospital, Mahidol University. A 4-mm punch biopsy was performed on each patient on the vertex area of the scalp and, subsequently, horizontally bisected at the level of 1 mm below the skin surface and studied by hematoxylin-eosin staining. The total number of hair follicles, the phase of each hair follicle in a normal hair cycle, the number of terminal hairs, intermediate hairs, vellus hairs, and hair follicular unit were also included in this study and compared to those in previously described reports.

Results: Of our 20 studied cases, the mean numbers of total hair follicle counts, terminal, intermediate, and vellus hair follicles were 28.3±9.2, 16.5±8.4, 5.0±4.6, and 6.9±7.0 respectively. The density of hair follicles in our study was statistically less than those found in Caucasians (p-value = 0.002) but more than those in African-Americans (p-value = 0.004) and in Koreans (p-value <0.001).

Conclusion: Data collected from previous publications provided only the number of hair follicles in other ethnic groups, but not from the Thai population. The number of hair follicles described in those studies may be unreliable and invalid in the interpretation of scalp biopsies in alopecia Thai patients. They may lead to a misdiagnosis of the disease. The density of hair follicles in Caucasians, African-Americans, Koreans, and Thai population were authentically different according to their ethnic backgrounds. This is important because the number of hair follicles should be considered when a pathologist evaluates the scalp biopsy specimens of alopecia patients.

Keywords: Hair follicle counts, Vertex, Thai population