1517 No Microscope Needed: A Macroscopic Presentation of Collagenous Colitis

Abstract

INTRODUCTION: Microscopic colitis (MC) is a common cause of chronic secretory diarrhea. Diagnosis has been considered to be histopathologic with otherwise normal-appearing colonic mucosa. However, accumulating evidence suggests distinct endoscopic features may be associated with MC. We present a rare case of MC that illuminates the importance of recognizing these macroscopic findings as they not only aid in diagnosis but also have significant management implications. CASE DESCRIPTION/METHODS: A 61-year-old female with rheumatoid arthritis presented with one month of watery, non-bloody diarrhea. She reported lower quadrant, crampy abdominal pain and a 20 lb weight loss. Her medications included pantoprazole 20 mg, escitalopram 20 mg, and ibuprofen three times weekly. Physical exam demonstrated diffuse abdominal tenderness and laboratory assessment revealed acute renal insufficiency and ESR of 28 (normal range: 0-15). Infectious stool studies were negative. A CT abdomen/pelvis revealed diffuse colonic wall thickening and mild mucosal hyperenhancement consistent with pancolitis. Colonoscopy revealed diffuse erythematous mucosa and multiple shallow, linear mucosal rents were created with minimal insufflation of CO2 during scope insertion. Targeted biopsies were taken and pathology demonstrated significant subepithlial collagen deposition consistent with a diagnosis of severe collagenous colitis (CC). DISCUSSION: While endoscopic findings may occur in up to 16.5% of patients with MC, only 1.1% of cases detail isolated linear ulcerations. Association with transmural inflammation is even more rare and to our knowledge this is the first report of CC with both radiographic evidence of pancolitis and discrete mucosal ulcerations. It has been hypothesized that collagen deposition reduces colonic compliance predisposing to mucosal tears that may herald colonic perforation. Although some studies suggest similar diagnostic yields between right versus left-sided biopsies (98.7% v. 98.9%), there are no descriptions of targeted biopsies in this condition. While our patient did not have any noted procedural complications, a flexible sigmoidoscopy may have been sufficient for a diagnosis. This case highlights an atypical presentation of CC with pancolitis and discrete endoscopic lesions that should prompt endoscopists to alter management. Flexible sigmoidoscopy with CO2 insufflation or water emersion should be considered in patients with macroscopic findings of MC, but the case should be aborted if deep mucosal tears occur.