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

## TL;DR

A rare case of a chronic nipple sinus caused by Demodex mites is reported, initially mistaken for a breast cyst and later linked to a severe COVID-19 infection.

## Contribution

This case highlights an unusual manifestation of Demodex folliculorum infestation in the nipple-areolar complex, expanding understanding of its clinical presentation.

## Key findings

- A 30-year-old woman presented with a discharging periareolar ulcer and nipple retraction following severe COVID-19.
- Histopathology revealed chronic granulation tissue heavily infested with D. folliculorum mites.
- Treatment with oral metronidazole and topical agents resolved the condition.

## Abstract

Demodex folliculorum 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 D. folliculorum mites within chronic granulation tissue. Following surgery, the patient was treated with oral metronidazole and topical agents (tea tree oil wash and sulfur soap).