Chapter 9, Page 9  

NON-NEOPLASTIC TUMOR-LIKE LESIONS, PREDOMINANTLY EPITHELIAL SPECIFIC TYPES OF GASTRIC POLYPS Focal Foveolar Hyperplasia (Foveolar Hyperplasia) Foveolar hyperplasia commonly accompanies many gastric diseases. It is a part of several reactive or inflammatory processes, such as chemical gastropathy and the gastritis of Helicobacter pylori. It is an integral part of Menetrier's disease, and is an expected finding on the gastric side of a gastrojejunal anastomosis. It often occurs at the margins of neoplasms, and in this setting it can be looked upon as the gastric mucosal equivalent of transitional colonic mucosa, a slightly distorted, elongated mucosa which is full of mucin and which is found next to or over virtually every colonic mass or localized inflammation. On occasion, foveolar hyperplasia is very focal or localized and produces a polyp characterized by elongated pits; little distortion, except for slight serration or dilatation; a normal deep glandular compartment; and a lamina propria that is normal or no more inflamed than the adjacent mucosa (figs. 9-16, 9-17, 9-18). However, this type of hyperplasia, composed of elongated foveolae or pits and nothing more, is not universally accepted as a polyp. It is included as a specific class of polyp by some investigators, particularly in northern Europe (20, 53, 59, 60, 70, 90); others, however, either do not identify it as a specific type of polyp or include it as a variant of hyperplastic polyp (66). The new WHO histologic classification of gastric polyps does not recognize this entity at all (101). Thus, focal foveolar hyperplasia is caught in the middle of a recognition tug-of-war. Part of the identity crisis results from the fact that foveolar hyperplasia is such a common reaction in the stomach. One author included focal foveolar hyperplasia in his classification of gastric polyps, but said that it is not a "true gastric polyp" but a reactive process (20); some think focal foveolar hyperplasia is due to a regenerative process in the healing phase of ulcers or erosions (78). Some tiny polyps have crowded pits with little intervening lamina propria, so that they resemble adenomas with foveolar epithelium, but their epithelium has no dysplastic features (fig. 9-18). Whatever the etiology, there are some small polyps that have no other features than an elongated pit compartment. These tiny lesions may be by far the most common of all gastric polyps, and account for over 90 percent in one series (53). They have a predilection for the antrum as do most other mucosal polyps. The natural history of such tiny bumps is not known, but it is tempting to imagine that some of them serve as precursors of larger polyps, such as hyperplastic polyps, that are also dominated by foveolar hyperplasia but which have other features such as intense inflammation and greater distortion. The potential relationship between focal foveolar hyperplasia and hyperplastic polyps is further discussed below.