Successful treatment of cutaneous phaeohyphomycosis caused by Exophiala lecanii-corni with voriconazole

MALDI-TOF MS identification of Exophiala species isolated in Japan: Library enrichment and faster sample preparation

Exophiala species cause chromoblastomycosis, mycetoma, and phaeohyphomycosis, which are occasionally fatally in immunocompromised patients. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides rapid and accurate examination of isolated bacteria and some fungal isolates, but the preparation method for filamentous fungi is complicated. In this study, 31 clinical isolates of Exophiala spp. in Japan were identified by MALDI-TOF MS with a library enriched by adding data. To simplify the sample preparation method, two modified methods were compared with the standard method for filamentous fungi. The agar cultivation sample preparation method reduced the time required for liquid culture and was considered suitable for clinical use. In 30 of 31 clinical isolates of Exophiala spp., the species identified by MALDI-TOF MS with the highest score matched the species identified by sequencing the internal transcribed spacer region. Exophiala dermatitidis, E. lecanii-corni, and E. oligosperma were identified above the genus level, while E. jeanselmei and E. xenobiotica were often not identified at the species level. The identification scores tended to be lower for less-registered strains in the in-house library. It is suggested that library enrichment and the modified preparation method may facilitate early diagnosis of rare fungal infections by Exophiala spp. in clinical laboratories using MALDI-TOF MS.

A Case of Recalcitrant Phaeohyphomycosis of the Face Caused by Exophiala lecanii-corni

We describe a case of recalcitrant phaeohyphomycosis caused by Exophiala lecanii-corni, which was previously reported as Exophiala jeanselmei, infection. A 63-year-old Japanese woman presented with a 15-year history of multiple pruritic erythematous patches and plaques on the face. Histopathological examination and fungal culture revealed phaeohyphomycosis by E. jeanselmei. The attempted treatments included 6 g/day 5-flucytosine (5-FC), 100 mg/day itraconazole (ITCZ), and local hyperthermia. 5-FC was effective initially, but the patient deteriorated after discontinuation. Subsequently, she was referred to our hospital. Histopathological examination showed granuloma with multinucleated giant cells with infiltrating fungal hyphae in the dermis. The causative fungus was finally identified as E. lecanii-corni by ribosomal RNA gene analysis. The patient improved after receiving 200 mg/day ITCZ orally for 15 months with local hyperthermia. In the present case, we confirmed the identification of E. lecanii-corni as the causative agent by molecular methods. We also emphasize the importance of combination therapy with antimycotic agents and local hyperthermia in phaeohyphomycosis.

Subcutaneous phaeohyphomycosis due to Exophiala jeanselmei following renal transplantation: A case report with a published work review of phaeohyphomycosis in Japan

We describe a case of cutaneous phaeohyphomycosis following renal transplantation and include a review of the previously published Japanese cases. A 40-year-old Japanese woman taking immunosuppressants following renal transplantation 6 years prior presented to our hospital with a subcutaneous lesion on her right leg. Skin biopsy revealed an abscess, and culture confirmed Exophiala jeanselmei to be the causative agent. Treatment with itraconazole combined with surgical drainage was effective, and the lesion disappeared after 15 months. Upon review of 128 Japanese phaeohyphomycosis cases, it was found that more than 80% of the cases occurred in patients aged more than 60 years, and most cases involved underlying diseases associated with immunodeficiency. E. jeanselmei was the most common etiologic fungus. Recently, however, the Exophiala species has been reclassified based on molecular identification, and cases due to E. jeanselmei decreased with the concomitant increase of cases due to Exophiala oligosperma and Exophiala xenobiotica. In approximately half of the cases, lesions were treated by surgical removal, with or without concomitant antifungal drugs. Itraconazole was the antifungal agent most frequently used. In many cases, the disease course was reported as either healing or improving. There was no difference in either treatment or prognosis based on the etiologic species of fungus.