The First Case of Tenosynovitis Caused by Thyridium endophyticum

Abstract

Letter to the Editor Clinical MicrobiologyDear Editor, Thyridium endophyticum, formerly known as Phialemoniopsis endophytica, is an uncommon mold species frequently isolated from the environment or plants [1][2][3]. To our knowledge, only one clinical case of T. endophyticum infection, manifesting as an asymptomatic subcutaneous nodule, has been reported [4]. We present a case of painful tenosynovitis attributed to T. endophyticum in a patient with preexisting medical conditions who underwent synovectomy and repair surgery in the right wrist. This possibly is the first documentation of T. endophyticum as a human pathogen capable of causing severe tenosynovitis. The Institutional Review Board of Chonnam National University Bitgoeul Hospital (CNUBH), Gwangju, Korea, approved this study and waived the requirement for informed consent (CNUBH-EXP-2024-003).A 72-yr-old man presented to the CNUBH with right wrist pain in January 2023. Four months prior, he had undergone surgery for a total tear in his right extensor pollicis brevis tendon at a lo-cal hospital. The patient's medical history included diabetes, dilated cardiomyopathy, atrial fibrillation, and seronegative rheumatoid arthritis, for which he received 10 mg of methotrexate weekly, and 20 mg of leflunomide and 5 mg of prednisolone daily. Physical examination revealed general swelling of the distal forearm and hand, although tenderness was not pronounced. A small ulcerative lesion was observed on the skin near the radial head (Fig. 1A and 1B). Magnetic resonance imaging of the right hand revealed multiple fluid collections, circular enhancement of the flexor and extensor tendon sheaths, and edema in the superficial soft tissues, skin, and carpal bones (Fig. 1C-1E). Laboratory tests revealed mild leukocytosis (10.96 × 10 9 /L, reference interval [RI]: 4.8-10.8 × 10 9 /L), an elevated C-reactive protein level (2.0 mg/dL, RI: 0-0.3 mg/dL), and an erythrocyte sedimentation rate of 43 mm/hr (RI: 2-9 mm/hr). Two months later, the patient underwent a dorsal tenosynovectomy and tendon transfer surgery. During the surgery, severe tenosynovitis, multiple tendon ruptures, granulation tissues, and a greenish