Two cases of adenocarcinoma occurring in sporadic fundic gland polyps observed by magnifying endoscopy with narrow band imaging

Gastric fundic gland polyps (FGPs) are common non-adenomatous gastric polyps arising from normal fundic mucosa without Helicobacter pylori (H. pylori) infection. Although systemic FGPs associated with familial adenomatous polyposis (FAP) often have dysplasia, there are few reports of dysplasia occurring in sporadic FGPs, especially when detected by magnifying endoscopy with narrow band imaging (ME-NBI). We experienced two cases of adenocarcinoma occurring in sporadic FGPs, and their ME-NBI findings were very useful for differentiating FGP with cancer from non-dysplastic FGP. A 68-year-old man and a 63-year-old woman were referred to our institution for medical checkup. H. pylori was negative in both patients. Endoscopic examination revealed a small reddish polypoid lesion on the anterior wall of the upper gastric body and several FGPs. ME-NBI showed an irregular microvascular architecture composed of closed loop- or open loop-type vascular components, plus an irregular microsurface structure composed of oval-type surface components which was different from that of FGPs. FAP was denied because of the absence of colon polyps and no familial history of FAP. Pathological diagnosis was adenocarcinoma occurring in sporadic FGP.