Disseminated nontuberculous mycobacterial infection mimic metastases on PET/CT scan

A 68-year-old man had malaise, weight loss, and enlarged right cervical lymph nodes. The first biopsy from a right cervical lymph node showed granulomas with negative acid-fast bacillus (AFB) staining, and he was treated for extrapulmonary tuberculosis with isoniazid, rifampin, ethambutol, and pyrazinamide. Symptoms persisted even after receiving antituberculosis drugs for 2 months. He was transferred to our center for F-18 FDG PET/CT scan under the suspicion of occult malignancy. The PET/CT scan showed increased FDG uptake in the right cervical lymphadenopathy and multiple bony lesions. The second biopsy from the FDG-avid cervical lymph node and bone marrow confirmed nontuberculous mycobacterial (NTM) infection. After another 6 months of adjusted antituberculosis therapy with isoniazid, rifampin, ethambutol, and clarithromycin, a repeat PET/CT scan showed remission of previous lesions.