[A Case of Perforative Peritonitis Due to Intestinal Metastasis from Lung Cancer].

We here describe a case of an acute peritonitis due to perforation of a small intestine tumor metastasized from a lung cancer. A 66-year-old man who had undergone a bladder cancer procedure 2 years ago and was hospitalized for the second operation, complained sudden abdominal pain. An enhanced abdominal CTrevealed a small amount of free gas and ascites in the abdominal cavity. On the same day, emergency exploratory surgery was performed with the diagnosis of perforative peritonitis. A laparotomy revealed a jejunal tumor with perforation 40 cm distal from the Treitz ligament. After surgery, the patient confessed that he had got a notice of the recurrence of lung cancer which had been treated 9 years ago. The pathological result indicated the lesion was metastasis from lung cancer. Although small intestinal metastatic tumor from lung cancer is rare, it should be considered when acute abdomen is observed.