A 79-year-old woman who had a past history of chronic renal failure 10 years earlier, tongue cancer (T2N2M0) 3 years earlier, and tuberculosis of the cervical lymph nodes 6 months earlier was suddenly admitted with the complaint of right chest pain on April 6, 2004. Right pneumothorax and mild pleural effusion were observed on a chest radiograph. There was no improvement in the patients collapsed lung despite the insertion of a chest drainage tube into the pleural cavity. Three thin-walled cavitary lesions were noted in the right lobe of segment 1 on computed tomography, and the cause of her pneumothorax was thought to be air leakage from the largest cavitary lesion adjacent to the visceral pleura. Partial resection of the right lung by video-assisted thoracoscopic surgery (VATS) was performed at the Department of Thoracic Surgery. Subsequently, it was determined that metastatic squamous cell carcinoma of the lung, corresponding to her tongue cancer, had invaded the visceral pleura adjacent to the largest cavitary lesion. Simultaneously, an epitheloid granuloma with caseating necrosis was observed adjacent to a partially thickened portion of this cavitary lesion. The epitheloid granuloma was found to be acid-fast bacilli-positive and a diagnosis of Mycobacterium tuberculosis pulmonary tuberculosis was made. We report a rare case of the coexistence of metastatic lung cancer originating from tongue cancer and active pulmonary tuberculosis diagnosed in the same large cavitary lesion.