Refractory tenosynovitis caused by Mycobacterium virginiense required repeated debridement: A case report and literature review

Mycobacterium virginiense is a slow-growing mycobacterium first described in 2016 as a novel species within the Mycobacterium terrae complex. To date, 8 cases of M. virginiense tenosynovitis or osteomyelitis have been reported, though none have been relapsed cases. A previously healthy 70-year-old Japanese man presented to a local orthopedic clinic with pain, swelling, and stiffness in his right middle finger. Initially diagnosed with trigger finger, he received multiple steroid injections. He was ultimately diagnosed with M. virginiense tenosynovitis. Despite synovectomy and antimicrobial therapy with ethambutol, rifampicin, and clarithromycin, a relapse occurred, necessitating a second tenosynovectomy, which led to remission. Antimicrobial therapy continued for approximately 20 months without recurrence. This case illustrates that M. virginiense can cause refractory tenosynovitis even in immunocompetent hosts. Delayed diagnosis and repeated local steroid injections may have contributed to disease progression and treatment failure in M. virginiense tenosynovitis.