Chronic Nipple Sinus Secondary to Demodex folliculorum Infestation: A Case Report

<i>Demodex folliculorum</i> mites are common commensals of human skin. They typically inhabit pilosebaceous units. While often asymptomatic, infestation can lead to demodicosis. Involvement of the nipple-areolar complex is rare and can mimic other benign or malignant conditions. Herein, we report a case of a 30-year-old, healthy, single woman who initially presented with symptoms suggestive of a simple breast cyst. Eight months later, following a severe COVID-19 infection, she developed a discharging periareolar ulcer with associated nipple retraction. Surgical exploration revealed a sinus tract connecting the nipple to the ulcer. Histopathology of the excised tissue unexpectedly demonstrated heavy infestation of pilosebaceous units with <i>D. folliculorum</i> mites within chronic granulation tissue. Following surgery, the patient was treated with oral metronidazole and topical agents (tea tree oil wash and sulfur soap).