Abenign polypoid adenoma of the first portion of the duodenum, which was diagnosed preoperatively, is reported. Case Report A. C., a 55-year-old white male, was admitted on April 26, 1955, complaining of mild epigastric pain for one month. For the past two years he had experienced intermittent epigastric distress occurring between meals and relieved by eating and lying down. The pain did not radiate, and improvement followed conservative therapy. There was no history of nausea, emesis, hematemesis, or diarrhea, nor had there been any bloody or tarry stools, jaundice, or weight loss. Physical examination was essentially negative except for epigastric tenderness on deep palpation. No abdominal masses were palpable. Gastric analysis with histamine showed no free hydrochloric acid. Otherwise all laboratory tests were within normal limits. Roentgenologic Studies: Roentgen study of the upper gastrointestinal tract demonstrated a smooth, round defect at the base of the duodenal cap, measuring about 2 em. in diameter. This was sharply defined and did not distort the duodenal bulb. It was immovable. The overlying mucosa seemed normal. No ulceration was seen. There was no obstruction. Impression: Benign polypoid tumor of the first portion of the duodenum without demonstrable pedicle. Surgery: At operation, April 29, a mass about 2 em. in diameter was palpable in the first portion of the duodenum. A transverse incision just distal to the pylorus on the anterior duodenal wall was made, and a polyp was found attached by a relatively small base to the anterior superior border of the duodenum. The pedicle was clamped and the polyp removed. The postoperative course was uneventful. Pathology: The microscopic diagnosis was polypoid adenomatous duodenal tumor with distinct hyperplasia and hypertrophy of Brunner's glands. There was cystic dilatation of several ducts with Brunner's glands in the wall. The growth showed edema and inflammation. There was no evidence of malignancy. Comment Since benign neoplasms of the duodenum are usually asymptomatic, the greatest number are found at autopsy. Symptoms when present are usually those of local irritability such as occur in duodenal ulcer or diseases of the stomach or pancreaticobiliary tract. Roentgen examination of the gastrointestinal tract is the only available method of preoperative diagnosis. This depends on the demonstration of a smooth filling defect within the duodenal lumen without associated deformity or evidence of infiltration. In differential diagnosis all other benign duodenal lesions must be considered. As in any other location, cancer can be ruled out only by histologic examination. Occasionally prepyloric gastric tumors can prolapseinto the duodenum and be misinterpreted as primary duodenal lesions. Figure 2 is an example of such an occurrence, showing (A) a polyp within the duodenum and (B) its return to its true gastric location.