[A case of pneumothorax due to pulmonary metastasis from breast cancer].

A 38-year-old woman was admitted because of left pneumothorax on March 16, 1991. She had undergone modified radical mastectomy in Dec. 1986. Chest roentgenogram on admission show a tumor shadow in the left upper lobe. She was diagnosed to have pneumothorax due to metastatic lung tumor. She underwent left upper lobectomy. Histologically poorly differentiated papillotubular adenocarcinoma was found and the cause of pneumothorax was thought to be necrosis of the tumor and direct invasion of the pleura.