A Case of Subcutaneous and Intranasal Phaeohyphomycosis Caused by Microsphaeropsis arundinis in an Immunocompromised Patient Misdiagnosed with Mucormycosis

Microsphaeropsis arundinis is a dematiaceous fungus capable of causing soft tissue infections known as phaeohyphomycosis, mostly in immunocompromised individuals. These infections arise from the traumatic inoculation of fungal materials into the subcutis, and can spread to adjacent subcutaneous tissues or via the lymphatics in a sporotrichoid manner. A 76-year-old man presented with diffuse erythematous plaques and swelling on both forearms and dorsal hands, and rhinalgia. He had been undergoing treatment for hypertension, angina pectoris, and diabetes. Histopathologic examinations of the skin, painful nasal septum, and molecular identification using internal transcribed spacer regions confirmed a diagnosis of subcutaneous and intranasal phaeohyphomycosis caused by M. arundinis. The patient was treated with oral itraconazole for over 5 months, and no recurrence was observed until the time of writing this manuscript. We report a rare case of subcutaneous and intranasal phaeohyphomycosis caused by M. arundinis and propose that confirmation of the causative strains is necessary, as it could affect the prognosis and treatment of the disease.