Fungal melanonychia caused by <i>Candida parapsilosis</i> successfully treated with oral fosravuconazole

Abstract

A 73-year-old healthy woman noticed black pigmentation on both thumbnails for 6 years. Upon her visit to our clinic, she had pigmented onychomycosis with onycholysis in the distal area. There was no evidence of paronychia. Direct microscopy using Zoomblue™ and histopathological examination showed aggregated blastoconidia. Fontana-Masson staining confirmed fungal melanin production. A combination of morphological features and genetic testing identified the isolates as Candida parapsilosis. Fungal melanonychia due to C. parapsilosis is rare, with only six cases reported since 1979. The minimum inhibitory concentration of the isolates was 0.25 μg/mL for itraconazole, less than 0.03 μg/mL for ravuconazole and 2.0 μg/mL for terbinafine. Both oral terbinafine treatment and itraconazole pulse therapy performed for 6 months were unsuccessful. The disease was ultimately cured with a 3-month treatment of oral fosravuconazole.