Subcutaneous phaeohyphomycotic cyst caused by Pyrenochaeta romeroi

Abstract

Pyrenochaeta romeroi is a rare agent of chronic, suppurative subcutaneous infections which ultimately lead to mycetoma. It has only rarely been reported from deep, non-mycetomatous infections. We describe a case of a subcutaneous phaeohyphomycotic cyst in a 45-year-old Indian female who suffered from verrucous plaque and a swelling (30 mm in diameter) on the right forearm that gradually increased in size over a period of 3 months. Direct microscopic examination with 10% KOH and histopathological investigation of exudates revealed septate hyphae without granules, the hallmark of mycetoma. The lesion appeared to be a subcutaneous phaeohyphomycotic cyst caused by P. romeroi. The suspected agent was recovered in culture, identified on the basis of morphologic features and its identification confirmed by sequencing of the internal transcribed spacer regions of rDNA. Treatment consisted of surgical excising of the cyst without any antifungal therapy. There was no relapse during a one-year follow-up and the patient was successfully cured. In vitro antifungal susceptibility tests demonstrated that itraconazole (0.5 microg/ml), isavuconazole (0.125 microg/ml) and posaconazole (0.5 microg/ml) had potent activity against this isolate of P. romeroi. High MICs were found with amphotericin B (4 microg/ml), fluconazole (>64 microg/ ml), voriconazole (4 microg/ml) and caspofungin (8 microg/ml). However, their clinical effectiveness in the treatment of P. romeroi infections remains to be evaluated.