RESUMO
A 61-year-old man visited our hospital because of nausea and vomiting. Abdominal CT revealed a severe stenosis of the ascending part of the duodenum but no evidence of tumors in the duodenum or pancreas. Upper gastrointestinal endoscopy showed severe stenosis of the ascending part of the duodenum with an ulcerative lesion. A biopsy of the site showed no evidence of malignancy. Nevertheless, duodenal and/or pancreatic cancer(s)could have caused the stenosis; therefore, we decided to perform an operation for the diagnosis and treatment of the obstruction. The surgery revealed severe stenosis of the ascending part of the duodenum with scar tissue. We performed subtotal stomach-preserving pancreaticoduodenectomy. Pathological findings showed pancreatic head cancer invading the ascending part of the duodenum. In this case, the diagnosis was difficult to make preoperatively because of the lack of an obvious neoplastic lesion. We believe duodenal invasion by pancreatic cancer without recognizing any tumor mass on CT is rare.