Subcutaneous Mycotic Cyst Caused by Roussoella percutanea in a UK Renal Transplant Patient

Fungi from more than 100 genera have been implicated in subcutaneous fungal infections, usually following traumatic inoculation of the etiologic agent. With the advent of molecular approaches to fungal identification and taxonomy, novel agents of subcutaneous mycoses are increasingly reported. In this manner, Roussoella percutanea, a novel species in Pleosporales, was described in 2014 from a subcutaneous mass in an immunocompetent male adult. Two additional cases involving renal transplant recipients were recently reported from patients resident in France and Germany, with several further cases discovered after analyses of historical culture collection isolates. Here, we describe a new case of subcutaneous R. percutanea infection, causing a mycotic cyst in a renal transplant patient resident in the UK. Although fungal infection was confirmed histologically, viable fungal isolates could not be recovered in culture from biopsy material and identification of the causative agent relied upon PCR amplification and sequencing of fungal rDNA genes. This is the fourth well-documented case of infection with R. percutanea in renal transplant patients, and the first reported from a patient resident in the UK. The current case illustrates the importance of molecular approaches for the identification of emerging fungal pathogens in culture-negative subcutaneous fungal infections.