Purpose: Background: 87 y/o Caucasian female with history of Hypertension, Hyperlipidemia, Vitamin D deficiency, osteoporosis, NSAID use, GERD, eczema was first seen in GI clinic 6 months ago for complaints of sour taste, dry mouth, intermittent watery non-bloody diarrhea, anorexia, fatigue, significant weight loss for the last 4 months. Abdominal exam was unremarkable. Methods: Lab profile including stool studies, thyroid function tests, amoeba antibody, serum transglutaminase/endomysial antibodies was negative. EGD revealed gastric atrophy and biopsy results were significant for Candidal esophagitis, H. pylori negative gastritis and duodenitis. Colonoscopy was suggestive of pancolitis mimicking ulcerative colitis, but the pathology was found to be consistent with collagenous colitis. A presumptive diagnosis of collagenous colitis versus IBD was entertained and patient was prescribed Loperamide, Mesalamine, Alendronate, Fluconazole, Prednisone and Azathioprine added later on as steroid sparing agent. Her treatment course was complicated by repeated admissions for recurrent flares on weaning steroids, Clostridium difficile colitis, compression vertebral fracture and prolonged use of steroids. Results: The case illustrates an atypical presentation of collagenous colitis in an elderly woman with evidence of pancolitis on colonoscopy. Conclusions: Collagenous colitis and lymphocytic colitis are clinically categorized under microscopic colitis with a predominant female sex predisposition. Most affected patients present in fourth decade of life and hence is more clearly documented in young adults. These patients typically have normal colonoscopies and diagnosis is made only on pathology. Our patient is atypical because of her late presentation in the eighth decade and colonoscopy findings of pancolitis suggestive of Inflammatory Bowel Disease.Figure: Friable, erythematous, edematous, loss of normal vasculature throughout with scattered superficial ulcerations.