Gastric adenocarcinoma of the fundic gland type: A review of the literature

Abstract Background and Aim Gastric adenocarcinoma of the fundic gland type (GA‐FG) is a newly described tumor entity but lacking consensus. This review summarizes the key features and controversies regarding this uncommon neoplasm. Methods We reviewed studies on GA‐FG published in English from 2007 to 2021. Results We found that 327 cases (340 lesions) have been reported. GA‐FG lesions originate from deep layers of the gastric mucosa, with the following characteristics on conventional white‐light endoscopy examination. These lesions, macroscopically identified as submucosal tumor‐like 0‐IIa, tend to have a whitish discoloration without inflammation, atrophy, or intestinal metaplasia in the background mucosa. Tumors located in the upper third of the stomach are usually solitary, with an average size <10 mm. Contrastingly, magnifying endoscopy with narrow‐band imaging mostly shows the absence of any demarcation line, with a regular microvascular pattern and regular microsurface pattern. GA‐FGs are covered with normal foveolar epithelium, forming a so‐called endless glands pattern in the deeper region, which are mainly composed of chief cells or parietal cells. Most tumors exhibit submucosal invasion, but lymphovascular invasion and nodal metastasis are rare. Regarding the treatment of GA‐FG, endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) are effective treatment methods. Conclusions GA‐FG is a rare tumor that typically follows a benign course. This neoplasm has distinct endoscopic and pathological features and could be treated by ESD or EMR.