A case of lung squamous cell carcinoma with metastases to the duodenum and small intestine.

Gastrointestinal metastasis of lung cancer is fairly rare, and metastasis to the duodenum is very uncommon. We report a case of duodenum and small intestine metastases of lung squamous cell carcinoma. The patient was a 66-year-old man. He was diagnosed with lung squamous cell carcinoma (T4N3M1 [mediastinum, cervical lymph node, and duodenum metastases], stage IV). He noted a sense of abdominal fullness on the evening of the day chemoradiotherapy was given, and emergency surgery was performed for suspected perforation of the digestive tract. Intraoperative findings included a tumor in the small intestine with a perforation at the tumor site; partial resection of the small intestine, including the tumor, was performed. Small intestine metastasis of lung cancer was diagnosed following histopathologic examination. When lung cancer patients complain of abdominal symptoms, it is important to consider gastrointestinal metastases in diagnosis and treatment.