A rare case of chromoblastomycosis in a renal transplant recipient caused by a non-sporulating species of Rhytidhysteron

We report a rare case of chromoblastomycosis caused by a non-sporulating species of Rhytidhysteron (Order Patellariales, Ascomycota) which was identified by molecular methods. The patient was a post-renal transplant recipient male aged 50 years and a resident of Delhi. The diagnosis was made by direct microscopy, histopathology and isolation of multiple colonies of the dematiaceous mould in pure culture. The samples used to recover the organism were obtained from a biopsy of one of the lesions occurring on his left foot and extending to the shin and thigh. The lesions comprised necrotic granulation tissue with indurated and thickened margins. After 2 weeks of therapy with itraconazole, 100 mg twice daily, the lesions partially retracted. However, the patient developed complications of acute abdominal pain with respiratory distress, necessitating admission to a tertiary-care hospital where he died due to multiple organ failure within 48 h. All attempts to induce sporulation of the fungal isolate on various mycological culture media were unsuccessful. Thereafter, sequencing of the 18S rRNA gene of the isolate and its comparison with GenBank database revealed that the fungus belonged to the genus Rhytidhysteron. As far as we are aware, this is the first case of human infection caused by a fungus of the Order Patellariales. The case underlines the relevance of molecular techniques as valuable tools for identification of non-sporulating opportunistic pathogenic fungi.