A Case of Chromoblastomycosis Caused by <i>Knufia epidermidis</i> Presenting as Multiple Dark Brown Papules in the Nasal Area

A Japanese man in his 70s presented with multiple blackish-brown papules on the nasal wing region, which had appeared 3 months prior to his initial visit. He was initially treated at a local clinic with clindamycin phosphate gel, but showed poor improvement. Subsequently, he visited our hospital for further evaluation. A skin biopsy was performed, granulomas consisting of histiocytes were observed in the tissue, and spore-like brown cells were observed sporadically within the granulomas. Fungal culture of biopsy tissue showed the development of black villiform colonies. Molecular biological identification confirmed the pathogen as Knufia epidermidis. Based on these findings, we thought it the patient with chromoblastomycosis due to K. epidermidis.He received 200 mg/day itraconazole (ITCZ) orally for 6 months, the multiple papules on the nasal region resolved, and the condition was considered cured. However, the papules recurred 2 months after discontinuation of ITCZ. ITCZ was restarted, and within 1 month, the recurrent papules had flattened. The patient remains on continuous ITCZ therapy at present.Recent years have seen a rise in reports of chromomycosis caused by rare and unrecognized pathogens. When diagnosing chromomycosis, it is necessary to identify of the species by molecular biological methods actively to avoid overlooking the diversity of causative pathogens.