Case report: Eosinophilic gastritis with localized eosinophilic infiltration presenting as a solitary deep-penetrating gastric ulcer refractory to potassium-competitive acid blocker

Introduction: Eosinophilic gastritis (EoG) is a rare disease characterized by eosinophilic infiltration of the gastric wall. The endoscopic findings of EoG are diverse. Case Presentation: We report a rare case of EoG in a 60-year-old woman presenting with a solitary deep-penetrating gastric ulcer accompanied by fold convergence. The lesion was resistant to potassium-competitive acid blocker therapy. Histopathological examination revealed dense eosinophilic infiltration (approximately 300 cells/high-power field) confined exclusively to the ulcer margin, with the surrounding gastric mucosa and other gastrointestinal sites showing no significant eosinophilic infiltration. EoG was diagnosed after excluding other possible causes. Corticosteroid therapy resulted in ulcer healing and an improvement in eosinophil infiltration. Conclusion: This case represents a rare instance of EoG presenting as a solitary gastric ulcer. EoG should be considered among the differential diagnoses for refractory gastric ulcer, even in the absence of diffuse mucosal eosinophilic infiltration.