[A case of lung cancer with small intestine metastasis with perforative peritonitis as the initial symptom].

Herein, we report a case oflung cancer with metastasis to the small intestine, with perforative peritonitis as the initial symptom. An 82-year-old man who had undergone subtotal gastrectomy and Roux-en-Y anastomosis for gastric cancer 8 years previously was admitted to our hospital with abdominal pain. We diagnosed the patient with gastrointestinal perforation, and a chest computed tomography(CT)scan showed a mass in the right lung. A laparotomy revealed a 4×3 cm sized intestinal tumor and intestinal perforation in the immediate vicinity ofthe anastomotic site. Segmentectomy ofthe small intestine was performed. Histological examination indicated that the tumor specimen was squamous cell carcinoma. Four months later, an abdominal CT scan showed multiple liver metastases, and the patient died 6 months after the operation because ofcachexia. At autopsy, a diagnosis ofsmall intestine metastatic tumor originating from squamous cell carcinoma of the lung was made. Although small intestine metastasis from lung cancer is rare, it should be considered when progressive abdominal symptoms are observed.