Biopsy study of polyps in the duodenal bulb.

To clarify the clinical and histological features of polyps in the duodenal bulb (DB), we studied, clinicopathologically, a total of 263 patients (179 male, 84 female) with polyps in the DB. The patients were 13-86 yr of age (average age, 57.1 yr). On endoscopy, a semipedunculated or pedunculated polyp with a relatively large size was seen in 33 patients, and small polyps, either single or multiple, were incidentally discovered in 230 patients. Histological examination of the biopsied specimens from polyps revealed gastric tissue in 182 cases (69.2%), cyst formation in 51 (19.4%), and other miscellaneous lesions (tubular adenoma, Brunner's gland hyperplasia, etc.) in 30 (11.4%). With regard to the gastric tissue, a "full-thickness" or "incomplete" body-type mucosa was identified in 27 cases of polyps, and hyperplastic surface epithelium was recognized in 155. Forty cases of hyperplastic surface epithelium-type polyps were subclassified as "pyloric"-type mucosa, because pyloric gland-like components seen under the surface epithelium were identical to those of the gastric antrum. It was reconfirmed that small polyps with little or no clinical significance could be produced by various histological features.