GASTRIC AND SMALL-INTESTINAL LESIONS AFTER PARTIAL STOMACH RESECTION WITH BILLROTH-II OR ROUX-EN-Y RECONSTRUCTION IN THE RAT

The evolution and phenotypic expression of mucosal lesions of the gast ric stump were investigated in male rats submitted to gastric resectio n with reconstruction by the Billroth II technique (BII with biliopanc reatic reflux, BPR) or by the Roux-en-Y procedure (without BPR). Anima ls were studied at 24, 36, 54 and 64 weeks after surgery and the pheno typic expression of lesions analysed using routine hematoxylin and eos in staining, immunohistochemical staining for pepsinogen isoenzyme 1 a nd histochemical procedures for mucins (paradoxical concanavalin A, ga lactose oxidase Schiff(GOS) and sialidase GOS reactions). BPR was foun d to be responsible for the formation of adenomatous hyperplasia (AH), increasing in incidence and size with time, since the Roux-en-Y proce dure failed to induce the gastric stump lesions observed after BII rec onstruction. AHs always occurred in the transition of the gastrojejuna l junction, a site offering special conditions for BPR influence, and were classified as gastric (G), intestinal (I) and G+I types according to their phenotypic expression. No pure I type AH was diagnosed at an y time point. The G and G+I types developed at approximately equal inc idences (i.e., G type 7/17, G+I type 10/17 at the 64th week). It was s uggested that both gastric and intestinal mucosal elements were stimul ated to proliferate by BPR, with the gastric mucosa tending to demonst rate AH. Intestinal type components of AH were found adjacent to the j ejunum and not at the stomach margin, indicating an origin from intest inal mucosa. No metaplasia of the gastric mucosa was observed in any a nimal after partial gastric resection. In 101 rats submitted to the BI I procedure, 5 mucinous adenocarcinomas were eventually diagnosed, mos tly located in the subserosa of the gastrojejunal junction. All carcin omas expressed the phenotype of cells of the small intestine. Evidence of malignant transformation within the gastric components of AH was n ot observed even at the 64th week. In conclusion, all lesions induced by BPR in the rat remnant stomach are benign, and the few true cancers that arise in association are derived from the small intestine.