Abstract
A 75-year-old man with the chief complaint of tarry stool was diagnosed as having a laterally spreading adenoma completely encircling the duodenum from the 2nd to the 3rd portion. The lesion had been followed by duodenoscopy and hypotonic duodenogram every six months. We finally carried out pancreaticoduodenectomy because adenocarcinoma was detected in the biopsy specimens six years after the initial diagnosis. The resected specimen revealed advanced cancer with regional lymph node metastasis. Duodenal adenoma is considered as a precancerous lesion and is recommended surgical resection. Because the lesion was mostly composed of adenoma with minimally adenocarcinoma in this case, it was hard to detect carcinoma tissue in the biopsy specimens. In addition, little changes in imaging findings also made difficult to make diagnosis of cancer at an early point of the clinical course. The patient might hesitate to undergo the highly invasive intervention without confirming the definite diagnosis of malignancy that might cause the prolonged observation. This case indicates the natural history of duodenal adenomas and a risk of long-term observation of them.
