Depressed adenoma of the stomach.

A "depressed adenoma" was detected in surgically removed stomachs. There were 40 such lesions (11%) of a total of 357 lesions of gastric adenomas. Macroscopically, these lesions often occurred along the lesser curvature of the stomach, had shallow depressions of a light-brown color, a round or oval shape with irregular margins, and could hardly be distinguished from a depressed early carcinoma. Although 14 of the lesions were detected preoperatively with confirmation by endoscopic biopsy, the other 26 remained unrecognized until the gross examination of the formalin-fixed specimens. Histologically, all were tubular adenomas of the intestinal type with varying degrees of epithelial atypia. Carcinoma in adenoma was present in 5% of these depressed lesions, in contrast to 2.5% of the conventional protruded adenoma. Thus, depressed adenoma seems to be a variant of gastric adenoma which has a somewhat higher malignant potential.