[Oxyntic gland neoplasia - case report and diagnostic dilemma]

The terminology oxyntic gland neoplasia is used for gastric gland lesions composed of atypical chief and parietal cells with no invasion, therefore, the diagnosis of fundic gland adenocarcinoma can not be made, but the lesion has not been completely removed, therefore, its total thickness can not be examined. The etiology of oxyntic gland neoplasias is currently unclear, with some sources linking them to proton pump inhibitors and antihistamine use. During endoscopic examination, their morphology is non-specific, they can appear as both flat and polypoid lesions, and are predominantly localized to the upper third of the stomach. If complete endoscopic mucosal resection can be carried out, no further treatment is required, therefore, they are considered to be lesions with an overall good prognosis. We present the case of an 84-year-old woman who was investigated for abdominal distention and underwent gastroscopy. A 1 cm flat polyp was seen in the gastric corpus, from which multiple biopsies were performed with almost complete removal. On histological examination, a well-circumscribed and well-differentiated lesion with expansive margins was observed in the deep mucosa, formed of atypical chief cells and parietal cells. These cells formed oxyntic gland-like structures. Pepsinogen reaction in the chief cells showed granular-like cytoplasmic positivity. H+/K+ ATPase reaction in parietal cells reflected granular-like cytoplasmic positivity. Diffuse, cytoplasmic positivity was observed in the lesional cells with MUC6. There was no sign of invasion. Based on morphology and immunophenotype, we concluded the lesion as oxyntic gland neoplasia with low-grade dysplasia. Oxyntic gland neoplasias require the attention from both clinical and pathological point of view, as they are rare entities with currently not fully understood etiology and prognosis. From a differential diagnostic point of view, fundic gland polyp, pyloric gland adenoma, and neuroendocrine tumor should be considered. Immunohistochemical reactions of pepsinogen, H+/K+ ATPase, and MUC6 can help to facilitate the definitive diagnosis. Orv Hetil. 2024; 165(27): 1053–1057.