CHANGES IN THE STRUCTURAL ELEMENTS OF THE SEBACEOUS HAIR FOLLICLE IN THE DIFFERENTIAL DIAGNOSIS OF NON-SCAR ALOPECIA

Background: The study of the pathogenesis of non-scar alopecia is associated with the study of the mechanisms of disruption of the biological rhythm of hair growth, with the determination of the ratio of % of hair in the anagen and telogen phases, without taking into account changes in the morphology of the sebaceous hair follicle and its structural elements. The functional significance of the structural elements of the sebaceous hair follicle - the hair sac, the outer and inner root sheaths - remains to be fully elucidated. There are no convincing data reliably determining changes in the hair sac, external and internal root vaginas depending on the development of a particular clinical variant of alopecia.

Aims: To study changes in the structural elements of the sebaceous hair follicle in non-scar alopecia.

Materials and methods: Histological and morphometric examination of biopsy material of the scalp was performed in 191 patients with non-scar alopecia and 20 patients from the control group.

Results: In the course of studying the thickness of the structural elements of the sebaceous hair follicle of the scalp at the level of subcutaneous fat in patients with non-scar alopecia of various origins, it was revealed that the hair sac is thinner than in the control group. The most significant changes were registered in patients with alopecia areata. A decrease in the thickness of the external root sheath was found in all the studied groups of patients with alopecia, with minimal values in the case of nested and diffuse hair loss. The thickness of the inner root vagina is thinner in diffuse, nesting and seborrheic alopecia, but not in androgenic alopecia.

Conclusions: In the absence of thinning hair, the most significant changes in the thickness of the hair sac, outer and inner root sheath are observed during the transition from the reticular dermis to the sebaceous gland, whereas in alopecia, structural thinning begins with subcutaneous fat.