Multiple gastric neuroendocrine tumors in a patient with parietal cell dysfunction and adenosine triphosphatase H+/K+ transporting subunit alpha gene variant

A 47-year-old woman presented with multiple gastric tumors, each up to 10 mm in diameter, in the gastric body and fundus without mucosal atrophy. White spots and numerous transparent, light-brownish, small, and rounded spots were observed in the background gastric mucosa. Biopsy specimens obtained from the tumors revealed gastric neuroendocrine tumors. The patient exhibited hypergastrinemia and achlorhydria and tested negative for serum parietal cell antibody, intrinsic factor antibody, and Helicobacter pylori infection. Moreover, no additional lesions were detected on imaging. These findings were inconsistent with Rindi's classification. The tumor was resected via endoscopic submucosal resection. Histopathological examination revealed gastric neuroendocrine tumors G2 infiltrating the submucosa with no atrophy of the gastric mucosa, dilated fundic glands, parietal cell protrusions, and hyperplasia of enterochromaffin-like cells. Immunohistochemically, the parietal cells were negative for both α- and β-subunits of H+/K+ ATPase, suggesting parietal cell dysfunction. A genomic variant was identified in adenosine triphosphatase H+/K+ transporting subunit alpha. After 7 years of treatment, there was no evidence of residual or metastatic lesions. Modification of adenosine triphosphatase H+/K+ transporting subunit alpha may be a significant factor in the pathogenesis of multiple gastric neuroendocrine tumors in the context of gastric parietal cell dysfunction.

Marked reduction in the number of white globe appearance lesions in the noncancerous stomach after exchanging vonoprazan for esomeprazole treatment: a follow-up case report

Recently, an association has been suggested between development of white globe appearance lesions in the noncancerous stomach and treatment with a potassium-competitive acid blocker or a proton pump inhibitor. We previously reported two cases with development of white globe appearance lesions after vonoprazan treatment, suggesting a similar association. Here, we present the follow-up report of one of those two cases, concerning a 68-year-old woman who developed multiple white globe appearance lesions 1 year after starting vonoprazan treatment for severe gastroesophageal reflux disease leading to esophageal stricture. The patient refused to continue vonoprazan treatment after the lesions developed, and esomeprazole was initiated instead. Three months later, most of the white globe appearance lesions had disappeared, without worsening of her gastroesophageal reflux disease. Histologically, mucosal structural changes induced by vonoprazan, such as parietal cell protrusion with oxyntic gland dilatation, remained unchanged, whereas the gastric glands became less packed and a small calcification in the concentrated eosinophilic material was observed in a remaining white globe appearance cyst after esomeprazole treatment. Here, we discuss possible pathogenic mechanisms of these dramatic gastric mucosal changes observed in the present case, based on our endoscopic and histological findings.