Abstract

Pressure-induced alopecia (PA) is an uncommon cause of hair loss seen in patients with a history of prolonged hospitalization, long surgeries, or immobilization. Typically, the hair loss is reversible with spontaneous resolution. However, with prolonged pressure, scarring alopecia can rarely occur. We present a case of PA and the biopsy findings that confirmed the diagnosis. A 29-year-old female presented for evaluation of a focal patch of alopecia on the occipital scalp. The clinical findings resembled alopecia areata and trichotillomania, so a 4 mm punch biopsy was obtained to help with diagnosis. The biopsy revealed a normal number of hair follicles, 100% of which were in the telogen phase. There was prominent perifollicular fibrosis and scattered foci of pigmentation with apoptotic bodies within most follicles. Additionally, there was prominent fat necrosis and numerous lipid laden macrophages and lymphocytes within the subcutaneous tissue. Trichomalacia and pigment casts were not seen. These findings, in addition to the patient’s clinical history, supported a diagnosis of pressure-induced alopecia. In PA, the distinguishing histologic features include a normal number of hair follicles with conversion of all follicles to catagen/telogen phase and fat necrosis. Features of scarring may or may not be present but can help with prognostication. We present this case to highlight the characteristic histologic findings of PA, the importance of obtaining an adequate sample which includes the subcutaneous fat, and identifying features of perifollicular fibrosis and scarring, as this influences the prognosis and outcome for the patient.