Trichosporon inkin subcutaneous infection in a rheumatoid arthritis patient

Abstract

A 74-year-old woman presented with painful ulcerative nodules on the left forearm. She had received systemic steroid therapy for rheumatoid arthritis for several years. On physical examination, there were four hemorrhagic ulcerative nodules with a linear distribution on the left forearm (Fig. 1A). These nodules had developed over the course of 2 months, and the number of lesions had increased despite systemic antibiotic therapy. There was no sign of systemic dissemination of the disease. Biopsy of a nodule demonstrated suppurative granulomatous infiltration (Fig. 1B); the hyphae stained positive with periodic acid-Schiff (data is not shown) and Gomori-methenamine silver stains in the dermis (Fig. 1C). The biopsy specimen was cultured in Sabouraud's dextrose agar supplemented with cycloheximide with incubation at 26 degrees C. A yeast-like creamy colony grew in 1 week. The colony became yellowish gray in color and the surface folded radially after 4 weeks of incubation (Fig. 2A). Microscopic examination revealed arthroconidia and blastoconidia (Fig. 2B), and urease activity was positive. The fungus was identified as Trichosporon beigelii by yeast biochemical card (YBC, Biomerieux Vitek, Inc., Hazelwood, MO, USA). The sequences of rDNA obtained from the colony were amplified using polymerase chain reaction (PCR) primer, analyzing the sequences of the 5.8S and 28S rDNA regions for the genetic identification of the Trichosporon species. The sequences of the PCR product matched the corresponding sequences of the T. inkin strain with 99% accuracy (Fig. 2C). The patient was given oral itraconazole for 8 weeks with good clinical results.