Collagenous Gastritis a Rare Disorder in Search of a Disease

A 19-year-old young male presented with abdominal pain and constipation. Subsequent EGD showed nodular gastric mucosa with simple gastric aspirate demonstrating acidic pH of 2.0. The gastric biopsy showed thick subepithelial band of about 15 microns that was confirmed to be collagen on Masson's trichrome stain along with inflammatory infiltrate. Colonoscopy and capsule endoscopy findings were unremarkable as well as the biopsy of the colon. Collagenous gastritis is a rare histopathological entity characterized by the presence of thick subepithelial collagen band of thickness greater than 10 microns along with intraepithelial lymphocytes and lamina propria lymphoplasmacytic and eosinophilic infitrates. Clinical presentation varies and depends more on the age of the patient with anemia or epigastric pain with nodular gastric mucosa being more common in children while diarrhea being more common in adults due to its increased association with collagenous colitis. The purpose of this case report is; (A) To define the endoscopic and histopathological features and progression of collagenous gastritis in this patient; (B) To compare these findings to those of collagenous sprue and collagenous colitis.