Characteristics of the Structural Components of Pilosebaceous Follicles in the Differential Diagnosis of Non-Cicatricial Alopecia

This study investigated the structural components of pilosebaceous follicles in 191 patients with non-cicatricial alopecia compared to 20 control patients. It found that hair follicles in alopecia patients were thinner than those in the control group, with the most significant thinning observed in alopecia areata. The external root sheath was consistently thinner across all hair loss groups, particularly in alopecia areata and telogen effluvium. The internal root sheath was thinner in diffuse telogen effluvium and alopecia areata but not in androgenetic alopecia. In non-alopecia patients, significant changes in follicle thickness occurred at the transition from the reticular dermis to the sebaceous gland, whereas in alopecia patients, thinning began in the subcutaneous fat tissue.