A Case of Phaeohyphomycosis Caused by Phaeoacremonium alvesii on the Dorsum of the Right Hand in Japan

Abstract

A man in his seventies without immunocompromised background presented with a slowly enlarging skin lesion on the dorsum of his right hand that had developed 6 months prior to his visit to our hospital. At the initial examination, a 3-cm brownish plaque associated with mild pain was observed on the dorsum of the right hand. Histopathological examination revealed a mass of hyphae in the subcutaneous tissue that was positive for periodic acid-Schiff and Grocott's stains. Fungal culture of the skin tissue yielded black-brown, downy colonies. Based on nucleotide sequencing of the internal transcribed spacer region and the β-tubulin gene, the organism was identified as Phaeoacremonium alvesii. After oral administration of terbinafine (TBF) at 125 mg/day was initiated, the lesions gradually improved. The strain exhibited slightly reduced sensitivity to TBF (minimum inhibitory concentration: 1 μg/mL). More than six months of oral therapy was required to achieve remission of the skin lesions. P. alvesii is a recently classified species, redefined in 2005 based on β-tubulin gene analysis, with only a few reported cases of human infection.