Infectious tenosynovitis of the hand is a serious condition with a high risk of morbidity. Mycobacterium tuberculosis is a rare cause of tenosynovitis, especially in regions where tuberculosis is no longer endemic, and presents significant diagnostic challenges. We present the case of a 42-year-old woman with no known history of or exposure to tuberculosis and a medical history of systemic lupus erythematosus on chronic immunosuppressive therapy who presented with swelling and erythema in the fifth finger of the left hand of 1-month duration. She underwent tenosynovectomy, and intraoperative cultures grew M tuberculosis. The patient completed an appropriate antibiotic regimen, and systemic workup revealed ring-enhancing lesions on brain MRI consistent with tuberculoma. We review the literature and current trends in the management of mycobacterial tenosynovitis, as well as the important teaching points of the case.