S3695 Collagenous Gastritis: A Rare Cause of Severe Iron Deficiency Anemia in a Basic Military Trainee

Abstract

Introduction: Collagenous gastritis is a rare inflammatory disease characterized by deposition of a thick subepithelial band of collagen and associated inflammatory infiltrate. This disorder has a reported prevalence of 13 per 100,000 esophagogastroduodenoscopies (EGDs) with a female predominance. Two distinct clinical phenotypes have been described: adult-onset characterized by diffuse gastrointestinal involvement and diarrhea, and pediatric-onset manifesting with abdominal pain and anemia. We present an interesting case of pediatric-phenotype collagenous gastritis to highlight this poorly-recognized disorder. Case Description/Methods: A 19-year-old male basic military trainee was referred for evaluation of incidentally discovered iron deficiency anemia. He denied any symptoms, overt blood loss, or NSAIDs. Physical exam was unremarkable. Labs revealed hemoglobin of 9.3 g/dL, iron saturation 7% and ferritin 15 ng/mL. The patient underwent EGD and colonoscopy for further evaluation. EGD revealed a diffusely nodular appearance of the gastric mucosa with areas with suspected atrophy under narrow-band imaging (Figures 1A, B). Colonoscopy was normal. Biopsies returned with a non-specific chronic gastritis without H. pylori. Abdominal computed tomography and additional work up for autoimmune gastritis, fecal H. pylori antigen, syphilis, and heavy metals toxins were all normal. Decision was made to repeat EGD for additional tissue sampling, including cold snared samples. Repeat gastric biopsies with expert GI pathologist review revealed collagenous gastritis, characterized by subepithelial deposition of a thick (greater than 10 µm) collagen band and associated inflammatory infiltrate (Figures 1C, D). Patient was lost to follow up due to disqualification for military service. Discussion: Collagenous gastritis is an exceedingly rare heterogeneous disease process of poorly understood causes and pathogenesis, with autoimmune conditions, medication effects, and infections theorized to be responsible. Numerous treatments have been reported with variable effect, including antisecretory agents, corticosteroids, immunomodulators, and hypoallergenic diets, along with micronutrient supplementation. Due to its rarity, a high level of suspicion is required by gastroenterologists and pathologists based on clinical and endoscopic findings. Our case helps to bring awareness to collagenous gastritis, and emphasizes the potential value for repeat tissue sampling with expert pathologist review.Figure 1.: A: Diffusely nodular appearance of the gastric mucosa with areas. B: Narrow-band imaging reveals areas of suspected atrophy. C: Multiple fragments of gastric mucosa with a prominent lymphoplasmacytic infiltrate within the lamina propria and occasional foci of subepithelial collagen deposition (red arrows). [Hematoxylin & Eosin, 50× magnification]. D: On higher magnification a focus of subepithelial collagen deposition may be seen associated with epithelial injury indicated by loss of foveolar mucin and detachment of the surface epithelium. [Hematoxylin & Eosin, 200× magnification].