Traumatic Alopecia in Trichotillomania: A Pathogenic Interpretation of Histologic Lesions in the Pilosebaceous Unit

The study investigated 10 patients with traumatic alopecia due to trichotillomania, focusing on histological examination of the affected scalp areas. Specific histological markers for traumatic alopecia were identified, including empty hair ducts, plucked-out hair bulbs, clefts in the hair matrix, catagen involution of empty outer root sheaths, Miescher's trichomalacia, and torn-off sebaceous glands. Other non-specific signs included the presence of catagen and anagen VI hairs, infundibular plugging, and melanin in keratin plugs and the dermal papilla. The study concluded that a skin biopsy could support the diagnosis of traumatic alopecia when clinical information is limited, although the histological picture may vary based on the intensity of hair pulling and the timing of the biopsy.