Abstract

Mucormycosis is a rare but grave fungal infection that is known to affect immunocompromised patients, especially diabetic patients. We present a 57-year-old female with a 4-month history of an enlarging non-healing ulcer on her left check that started as a nodule after her COVID-19 diagnosis. Physical exam revealed a large, ulcerated lesion with visible muscle and subcutaneous tissue on the left face with extensive surrounding induration. Patient also endorsed abdominal pain, fever, chills and night sweats. Patient was previously treated with multiple bouts of antibiotics and steroids. A punch biopsy of the ulcer edge demonstrated prominent dermal inflammation that was composed of large collections of plasma cells with background lymphocytes and neutrophils. While plasma cells were polytypic, immunostains for IgG and IgG4 showed increased IgG4+ plasma cells (~50% IgG4/IgG plasma cell ratio). Culture studies were negative whereas serum IgG4 level was found to be increased (148 mg/dL). The possibility of IgG4-related disease was raised, however, due to higher suspicion for infectious etiology, the specimen was sent for microbial PCR study that detected Mucor DNA. The case highlights the fact that isolated IgG4 in the serum or IgG4+ plasma cells in tissue does not constitute IgG4 disease. Elevated IgG4 levels have been previously reported in Mucor infections, but this is the first such case in skin. COVID-19 infection may also have a role in immune dysfunction, leading to opportunistic infection in the first place.

Financial Disclosure:
No current or relevant financial relationships exist.