Collagenous Gastritis Is an Underdiagnosed Cause of Anemia and Abdominal Pain: Systematic Scoping Review.

Background: Collagenous gastritis (CG) is a rare disease characterized by infiltration of the lamina propria with mononuclear cells and subepithelial deposition of collagen. Due to its nonspecific presentation, it is often misdiagnosed. The clinical characteristics, endoscopic, and histopathologic features, and treatment outcomes of CG have not been well defined.