Pancreatic (acinar) metaplasia of the gastric mucosa. Histology, ultrastructure, immunocytochemistry, and clinicopathologic correlations of 101 cases.

The occasional finding within the gastric mucosa of unidentified epithelial cells with morphological features closely resembling those of pancreatic acinar cells has prompted us to investigate a retrospective series of 8,430 consecutive gastric biopsies and of 126 surgical specimens of gastric resection and total gastrectomy. The aims of the study were to morphologically and immunocytochemically characterize these cells, to define their actual prevalence in a large series of unselected cases, and to assess the clinicopathologic correlates of their occurrence. Pancreatic acinar-like cells characterized by abundant cytoplasm, which was acidophilic and finely granular in the apical and middle portions and basophilic in the basal compartment, have been identified in 101 cases (84 gastric biopsies and 17 gastrectomies). These cells, arranged in nests or in variably sized lobules among the gastric glands, were morphologically indistinguishable from pancreatic acinar cells, both by light and by electron microscopy. Furthermore, they were consistently immunoreactive for pancreatic lipase and trypsinogen and, in 75% of the cases, for pancreatic alpha-amylase. The appearance of these cells within the gastric mucosa was correlated significantly with chronic gastritis (p = 0.032) and with the simultaneous occurrence of intestinal and pyloric types of gastric metaplasia (p = 0.021). The findings indicate that this is a previously unrecognized pancreatic (acinar) metaplasia of the gastric mucosa, clinically and morphologically distinct from pancreatic heterotopia.