Phaeohyphomycosis is a mycotic infection caused by chromomycotic fungi that produce hyphae in tissues.　Phaeohyphomycosis is commonly associated with immunocompromised hosts. Here, we report two cases of phaeohyphomycosis on the fingers in immunocompromised hosts, one of which was diagnosed by direct microscopy. Case 1 was of an 87-year-old male with lung cancer (stage IVB) under palliative treatment who developed a subcutaneous solitary abscess on his left ring finger. He received a scratch wound on his left hand three months prior. A direct microscopic examination of the pus revealed a lot of hyphae. Mycological cultures after 18 days of incubation revealed filamentous colonies. Slide culture technique for fungi showed hyphae with phialides that ended in a wide-angled collarettes. DNA sequence analysis using the cultured fungus identified Pleurostomophora richardsiae. Case 2 was of an 80-year-old male with poorly controlled type 2 diabetes mellitus who developed a small nodule on his right thumb two months prior. Mycological cultures after 21 days of incubation revealed black filamentous colonies. DNA sequence analysis using the cultured fungus showed high homology with Exophiala xenobiotica. In both cases, treatment with oral terbinafine was effective. Recently, the number of patients with phaeohyphomycosis has increased; therefore, it is important to consider this disease in differential diagnosis cases, particularly for immunocompromised patients with antibacterial drug-resistant abscess on the fingers. A direct microscopic examination of the pus may be useful in making a rapid diagnosis, which is conducive to phaeophyphomycosis.

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This single-center, exploratory, retrospective observational study explores the efficacy and safety of fosravuconazole L-lysine ethanolate (NAILIN® capsule, “F-RVCZ”) in patients with onychomycosis who were switched from a topical antifungal drug (“topical drug”). The average duration of administration of the topical drug was 24.3 months. All patients were switched to F-RVCZ due to insufficient effects. The average involvement ratio at the start of treatment was 7.8, and many patients had severe disease. However, the clinical cure rate at 48 weeks was 62.5%; therefore, F-RVCZ had a high efficacy when switching from topical drugs. Adverse reactions were observed in 13 patients (25.0%), three of which led to discontinuation. All adverse reactions were known symptoms and were resolved after the discontinuation of F-RVCZ. F-RVCZ, which has relatively few interactions and safety concerns, has a high therapeutic effect after a short-term administration of 12 weeks even in patients who report insufficient efficacy with the use of topical drugs.

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