A 73-year-old male visited our hospital with a complaint of appetite loss in 2001. Endoscopic examination showed a semipedunculated polypoid lesion, about 7 mm in size, at the opposite side of the papilla Vater. Endoscopic biopsy revealed adenocarcinoma. Endoscopic mucosal resection was performed after confirmation of negative non-lifting sign, because the lesion was measured less 10 mm in largest diameter. The resected specimen was 7×7×6 mm in dimensions and histologically consisted of tubular adenocarcinoma limited to the superficial layer of the duodenal mucosa (m, ly 0, v 0) . Cut-end of the lesion was free of carcinoma. Duodenal malignant lesion is relatively rare, especially early cancer. Meanwhile, there are many borderline cases of epithelial tumors between benignancy and malignancy in the duodenum. Therefore, complete excisional biopsy such as endoscopic mucosal resection is recommended.
