Collagenous gastritis: Histopathologic features and association with other gastrointestinal diseases

Collagenous gastritis (CG) characterized by the deposition of a subepithelial collagen band and accompanying inflammatory infiltrate is a rare disorder. The natural history and pathogenesis of CG remain unclear. We describe the histologic features (23 gastric, 18 duodenal, and 4 colonic biopsies) and clinical findings of an additional 12 cases. Histologic features including active or chronic inflammation, surface epithelial injury, intraepithelial lymphocytosis, intestinal metaplasia, and Helicobacter pylori, and measurement of thickness of subepithelial collagenous band were evaluated in gastric biopsies. The clinical features, endoscopic findings, and follow-up were obtained and correlated with histologic features. There was an even number of males (n≤6) and females (n≤6). Four patients were children/young adults, 3 of whom (75%) presented with anemia and gastric nodularity. Eight patients were adults, 6 of whom (75%) had an associated autoimmune disease (1 with Hashimoto thyroiditis and polymyositis) or other intestinal disease (3 with celiac sprue, 1 with collagenous colitis, 1 with collagenous sprue), in contrast to none in the 4 children/young adults, P≤0.06. The range of subepithelial collagen thickness was 15 to 120m in CG. The collagenous layer showed surface epithelial injury and entrapped inflammatory cells. On presentation, the thickened collagen distribution in the antrum and body was variably patchy and diffuse. Four (33%) patients showed lymphocytic gastritis (3 within the same biopsy); one of these patients also had celiac sprue and another had collagenous sprue. Three (25%) patients had celiac sprue (2 had duodenal biopsy proven and 1 had a clinical diagnosis of celiac sprue). An additional patient had duodenal biopsies showing collagenous sprue. Four patients had follow-up biopsies during a 3 to 119-month period after the diagnosis of CG. CG persisted on the follow-up gastric biopsies in 3 (75%) of the 4 patients, and the other patient had lymphocytic gastritis, a finding not seen in previous biopsies. CG is a rare disorder with a distinct presentation and association in pediatric and adult patients. An absence of associated intestinal and autoimmune diseases characterizes the pediatric population. Association with lymphocytic gastritis, celiac or collagenous sprue, collagenous colitis, and autoimmune disorders are frequently seen in adult patients.