Fundic Gland Polyps
Fundic gland polyps are the most common type of polyps detected at EGD in Western countries. In a large recent pathologic study, fundic gland polyps were diagnosed in approximately 6% of patients who had an EGD and represented 74% of all gastric polyps submitted for histopathologic evaluation. Endoscopically, fundic gland polyps are usually multiple, small (<1 cm), and appear smooth, glassy, and sessile. By narrow band imaging they have a honeycomb appearance with dense vasculature, a nonspecific pattern that also can be seen in hyperplastic polyps.
When first discovered, fundic gland polyps were believed to be hamartomatous. However, their association with PPI use, confirmed in a number of studies, suggests that mechanisms related to the suppression of acid secretion by proton pump inhibition may be involved in their pathogenesis.[4,5]
Histopathologic Features and Diagnostic Criteria
Histologically, fundic gland polyps consist of one or more dilated oxyntic glands, lined by flattened parietal and mucous cells (Figure 1). Fundic gland polyps are among the most characteristic lesions of the stomach: the recognition of the dilated oxyntic glands with flattened parietal and mucous cells in slides stained with H&E is immediate and unequivocal (Figure 1B and C). One caveat is that when the surface of a polyp is eroded the regenerative appearance may be misinterpreted as dysplasia. True dysplasia, particularly high grade, is exceedingly rare and is virtually limited to fundic gland polyps found in patients with polyposis syndromes. No special stains or molecular studies are warranted.
Fundic gland polyp. (A) Endoscopic view of multiple fundic gland polyps in the body of the stomach in a patient taking PPIs. (B) Low-power photomicrograph showing the characteristic dilatations of oxyntic glands. There is only minimal stroma, and the surface foveolar epithelium is either normal or focally flattened. (C) High-power photomicrograph showing a dilated oxyntic gland lined by cuboidal parietal cells (a); as the gland dilate more (right), both mucous and parietal cells progressively flatten (b and c).
The finding of multiple characteristic polyps in the oxyntic portion of the stomach in a patient taking PPIs is essentially diagnostic of fundic gland polyps. Generally, when first encountered, one or more representative polyps should undergo a biopsy examination to confirm the diagnosis. Large polyps (>1 cm in diameter) should be removed entirely to confirm the diagnosis because fundic gland polyps rarely exceed this size. A biopsy specimen from the polyp in these cases is not adequate because if the polyp is not of the fundic gland type, biopsy sampling may not include crucial areas of possible dysplasia or neoplasia. In addition, a thorough visual inspection of the remaining polyps should be made; any lesion that appears significantly different from the others should be undergo a biopsy examination, or, if possible, be removed. Specifically, size larger than 1 cm, ulceration, and unusual location such as the antrum should prompt a more aggressive approach. When fundic gland polyps are found in a young patient, especially if numerous (eg, ≥20), the possibility of a polyposis syndrome should be considered. Individuals with familial polyposis syndromes typically are younger than the average patient with fundic gland polyps (mean age, 40 y),[7,8,9] and occasionally have polyps in the antrum. When gastric polyps are associated with duodenal adenomas a familial polyposis syndrome strongly should be considered and colonoscopy should be recommended.
Fundic gland polyps rarely are found in stomachs affected by H pylori infection and, therefore, in the absence of a familial polyposis syndrome, concerns about gastric cancer are moot. Nonetheless, when polyps are innumerable or large (>1 cm) there may be cause for concern regarding eventual outcome. Although no guidelines exist, we suggest that when either more than 20 polyps are present or their size is larger than 1 cm one should consider reducing or preferably stopping the medication to assess whether this will result in regression of the polyps. If regression occurs, it is unknown whether PPIs can be reinstituted. Practically, if surgical therapy is not an option, one might consider a different PPI and at the minimally effective dose. Although there does not seem to be a correlation between serum gastrin levels and the presence of fundic gland polyps, it may be worthwhile to measure gastrin levels in these patients. A high level (>400 pg/mL) suggests profound acid suppression. If the patient is not an intrinsic hypersecretor and does not have a gastrinoma or Zollinger–Ellison syndrome, PPIs should be withdrawn, and, if gastroesophageal reflux disease symptoms persist, replaced with an H2-receptor antagonist. Recent reports of gastric carcinoids associated with profound PPI-induced acid suppression[14,15] and the increasing awareness of other potential adverse effects (eg, interference with the absorption of a variety of other medications, possible hip fracture, and Clostridium difficile infection) have provided further impetus to using PPIs less often and at the minimal effective dose.[15,16,17,18,19,20,21,22]
Clin Gastroenterol Hepatol. 2013;11(11):1374-1384. © 2013 AGA Institute