Abstract

A 47-year-old male coal miner presented with several months of altered mentation and new onset seizures, hypothyroidism, and rapid cognitive decline, as well as incidentally noted scaly plaques on the bilateral hands, flanks, and buttocks. Skin biopsy showed palisaded granulomatous dermatitis with scattered yeast forms, highlighted on GMS staining. Both clinically and histomorphologically, the fungal process most closely resembled blastomycosis, although other endemic fungal infections were considered. However, both tissue and serological fungal testing were negative for Blastomyces or other endemic fungi. Universal fungal PCR performed on the skin biopsy at an outside institution revealed Malassezzia restricta. Concurrently, serologic and cerebrospinal fluid testing failed to reveal an infectious, neoplastic, or specific autoimmune etiology for the altered mental status; a diagnosis of nonspecific autoimmune encephalitis was rendered. Itraconazole therapy was initiated with concurrent intravenous methylprednisolone, and the rash and mental status improved. Malassezzia restricta is a common cutaneous yeast commensal often identified using culture-free methods but infrequently recovered using culture. It is associated with seborrheic dermatitis and folliculitis but is uncommonly associated with invasive cutaneous fungal infections. It does not grow on olive oil-potato dextrose agar; instead, high plating concentrations on specialized modified Dixon or Leeming and Notman agar must be used. Hence, molecular detection is often preferred. Rare central nervous system infections have been reported in immunocompromised patients. Although autoimmune encephalitis remained the most likely diagnosis in this case, the possibility of relation to M. restricta infection could not be excluded, and the patient remains on itraconazole with improved cognition and rash.