Rare Case of Subcutaneous Phaeohyphomycosis Caused by Exophiala jeanselmei

Abstract

Abstract Introduction/Objective Phaeohyphomycosis is a neglected tropical infection caused by dematiaceous fungi containing melanin in their cell wall. Currently, the prevalence of phaeohyphomycosis is very low in the United States compared to other mycotic agents. Trauma often precedes phaeohyphomycosis, and there are a limited number of cases associated with healthcare settings. This case report describes a nosocomial phaeohyphomycosis caused by Exophiala jeanselmei. Methods/Case Report A 60-year-old male with multiple myeloma, on immunosuppressive therapy, presented with a large fluctuant mass on the dorsum of his right hand. The mass had developed 6 months ago as a hematoma following a blown vein during a blood draw. Despite treatment with antibiotics, the mass continued to grow. The patient underwent surgical excision of the lesion, and the purulent aspirate was sent to the microbiology lab. Aerobic, anaerobic, mycobacterial, and fungal cultures, along with Gram and AFB stains, were performed. Direct microscopy of the aspirate revealed numerous leukocytes and few yeast cells. No sclerotic bodies were observed. Fungal growth with black pigmentation was observed during the second week of incubation. Colonies initially appeared smooth black and mucoid, later transforming into raised dome-shaped structures with a suede-like texture. Microscopic analysis revealed budding yeast cells and subglobose to broadly ellipsoidal germinating cells, which developed into short torulose hyphae before gradually transforming into unswollen hyphae. The isolate was further identified through D2 rDNA sequencing, revealing a 100% match for Exophiala jeanselmei. The patient was prescribed a one-month course of itraconazole treatment. The patient is progressing well during follow-up. Results (if a Case Study enter NA) NA Conclusion This case emphasizes the need for heightened clinical awareness in diagnosing phaeohyphomycosis, particularly in healthcare environments. Unique traumatic events like venepuncture should raise suspicion of phaeohyphomycosis. Culture and molecular diagnostics play a crucial role in confirming fungal causes and guiding treatment, leading to better patient outcomes.