Duodenal adenomas in familial adenomatous polyposis: their structure and cellular composition with particular reference to endocrine hyperplasia.

134 duodenal biopsies from 14 patients with familial adenomatous polyposis were evaluated by light microscopy for the presence of adenoma. Staining reactions for endocrine cells were applied. 90 biopsies contained adenoma, almost all of the tubular type (98%) with dysplasia, ranging from mild to moderate. Accompanying hyperplasia of argyrophil and argentaffin endocrine cells was found in 91% and 64% of the adenomas, respectively. Based on histological criteria it is concluded that the risk of carcinoma development in the duodenum could equal that in colon and rectum. The observation of endocrine hyperplasia is new, and further investigations are needed before the significance of this finding can be evaluated.