A case of phaeohyphomycosis infected with Exophiala jeanselmei

A 77-year-old Japanese man presented with an asymptomatic tumor affecting the dorsum of the right hand. He had been treated for double cancer in the prostate and lung associated with multiple metastases. On examination, there was an elastic hard tumor in the subcutaneous tissue with limited mobility. Excisional biopsy showed that the tumor included yellowish white-colored atheromatous materials, from which fungus was detected in the culture. Histopathologically, there were numerous spores and hyphae with PAS positive stain within granulomas. Based on a molecular biologically technique, type 6 of Exophiala jeanselmei was identified from the tumor. To our knowledge, only one case of phaeohyphomycosis infected with Exophiala jeanselmei has been reported in the northeast area of Japan. The solitary tumor in our case is reminiscent of more common skin diseases such as epidermal cyst. However, for proper diagnosis and therapy, we should not neglect the possibility of fungal infection in cases of compromised hosts.