Pediatric-onset collagenous gastritis – Presents with abdominal pain and severe anemia with an inflamed and/or nodular stomach and normal-appearing colon. There is no known etiology.
Adult-onset collagenous gastritis – Associated with collagenous colitis and presents with voluminous nonbloody diarrhea. Etiology is possibly secondary to autoimmune, infectious, and medication-induced causes.
Esophagogastroduodenoscopy (EGD) is important for diagnosis and to rule out other causes of symptoms.
K52.9 – Noninfective gastroenteritis and colitis, unspecified
711499009 – Collagenous gastritis
Differential Diagnosis & Pitfalls