A 21-year-old woman presented with nausea, vomiting, decrease in appetite, and weight loss of 6 months and right chest pain of 5 days' duration. Earlier diagnostic work-ups had been inconclusive, and she was referred for the evaluation of the bilateral lung lesions as seen on her chest x-ray. Thoracic computed tomography scan showed a 6-cm mass in the right lower lobe, a minimal right pleural effusion, and a peripheral 2-cm cavitary nodule in the inferior lingular segment. Ultrasonography-guided transthoracic cutting needle biopsy of the right-sided mass and following right lower lobectomy both yielded benign specimens pathologically assessed as "inflammatory myofibroblastic tumor." The chest x-ray and thoracic computed tomography scans obtained 1 month following the thoracotomy showed spontaneous and almost complete resolution of the left-sided nodule. In follow-up 1 year after the surgery, no clinical, laboratory, or radiologic recurrence was detected. She is being closely followed as an outpatient.