Gastric fundic gland polyps.

Sporadic fundic gland polyps account for approxmately 50% of all gastric polyps and may be observed in .8% to 1.9% of patients undergoing upper gastrointesinal endoscopy (Table 1).1,2 They are encountered more ommonly in middle-aged women, although they are lso observed in men and in about 0.3% of pediatric atients undergoing endoscopy with an average age of iagnosis of 14.4 years.3 Fundic gland polyps also occur n 12.5% to 84% of patients with familial adenomatous olyposis (FAP).4 In this setting the occurrence is equivlent in women and men and polyps are observed at uch younger ages. Fundic gland polyps may be single or multiple, but sually fewer than 10 polyps are observed in the sporadic etting, although 50 or more polyps have been reported. hese polyps always occur in the body and fundus of the tomach. In FAP, numerous fundic gland polyps are sually observed, often numbering in the hundreds (Figres 1A–B). The polyps may cover the entire surface of he acid-secreting epithelium and even coalesce to give a matted” appearance of the mucosal surface. Polyps in oth the sporadic setting and in FAP are usually 1-mm o 5-mm in diameter, although larger polyps are oberved. They are sessile, hemispherical-shaped elevations, ith the occasional appearance of a “waist” but not a talk. Their color is pale pink, resembling surrounding ucosa. At endoscopic biopsy the polyps usually “chunk ff” or detach entirely at the base, unlike other gastric olyps. These characteristics together usually make funic gland polyps endoscopically distinguishable from ther types of gastric polyps.1 Histologically, fundic gland polyps are characterized y cystically dilated and irregularly budded fundic lands, which are lined by flattened parietal cells, chief ells, and variable numbers of mucous neck cells.4 The verlying surface and foveolar gastric epithelium is typcally nondysplastic. Surrounding mucosa is uniformly ormal both morphologically and histologically and conurrent atrophy is seldom observed. The pathogenesis and cancer risk of fundic gland olyps is poorly understood. These lesions have usually een considered hamartomas, although up to 25% of AP-associated fundic gland polyps and 1% of sporadic ypes are now known to show foveolar epithelial dysplaia, which is often proceeded by dysregulation of epitheial proliferation.5 Gastric cancer has been reported in AP patients with fundic gland polyps, even arising rom them,6,7 although the lifetime risk of gastric cancer n FAP is estimated to be only 0.6%,8,9 but may be igher in some countries such as Japan.10 Fundic gland polyps in FAP arise from mutational nactivation of the adenomatous polyposis coli (APC) ene, which is the gene mutated in that condition,2 hile sporadic fundic gland polyps are usually caused by ctivating mutations of the beta-catenin gene.4,11 Both enes are involved in the same cell growth-signaling athway,12 which explains why mutations in either gene an give rise to fundic gland polyps that are histologially similar. When dysplasia occurs in fundic gland olyps it is usually in polyps with mutations of the APC ene. This observation appears to explain why dysplasia s sometimes observed in the fundic gland polyps of FAP, ut seldom in sporadic fundic gland polyps.13 c