Abstract
Collagenous gastritis is a rare form of gastritis that affects both children and adults. The underlying pathophysiology is not well-understood, and as a result, there are limited options for treatment. We report a case of a young female patient with chronic diffuse abdominal pain, nausea, regurgitation, and early satiety with esophagogastroduodenoscopy showing gastric erythema, atrophic gastric body, and significant gastric nodularity. Biopsies revealed focal erosion and increased subepithelial collagen deposition. She was successfully managed with intravenous vedolizumab infusions after initial therapy with topical budesonide did not result in clinical or endoscopic improvement.