A tiny gastric adenocarcinoma of fundic gland type mimic polyp

A 44-year-old woman with no known underlying diseases developed epigastric pain and abdominal fullness for 2 weeks. She denied prior proton pump inhibitor use and a family history of polypoid syndrome. Esophagogastroduodenoscopy revealed a 0.4-cm polyp with relatively intact mucosa on the esophago-cardiac junction (Figure 1A,B). The mucosal pattern of the stomach showed no atrophic change; the Campylobacter-like organism test showed negative, and the biopsy showed no Helicobacter pylori. Identified. The etiology was suspected to be a fundic gland polyp by conventional endoscopy. However, pathological findings revealed adenocarcinoma. The patient underwent endoscopic submucosal dissection and pathological findings showed a well-differentiated gastric adenocarcinoma tumor, fundic gland type; the tumor dimension was 0.4 × 0.3 cm, and the greatest invasion depth was 0.1 cm above the muscularis mucosae (Figure 2).

Gastric adenocarcinoma of the fundic gland type (GA-FG), a novel rare variant of gastric adenocarcinoma (accounting for 1% of patients with early gastric carcinoma), presents with atypical cells with differentiation toward the fundic gland and has been added to the 2019 edition of the World Health Organization's list. The most common features of tumors are their whitish appearance, dilated vessels with branching architecture, and background mucosa without atrophic changes. Furthermore, at low magnification, GA-FG can mimic a fundic gland polyp.¹ Some reports showed regular microvascular patterns under magnifying endoscopy in partial cases.²

In our case, the small size and unimpressive endoscopic appearance of the polyp further emphasize that these alone cannot predict the histology of the polyp. Although the majority (70%–90%) of gastric epithelial polyps are fundic gland polyps or hyperplastic polyps and are often incidental findings on endoscopy. Gastric polyp histology cannot be reliably distinguished by endoscopic appearance; therefore, a biopsy or polypectomy is warranted when polyps are detected.³

The authors declare no conflicts of interest.

Written informed consent was obtained from the patient.