S1701 Can’t Hold It In: A Case of Collagenous Colitis After Rectal Prolapse Surgery

Abstract

INTRODUCTION: Microscopic colitis (MC) is a common, though underdiagnosed, cause of non-bloody watery diarrhea. MC’s two subtypes, collagenous and lymphocytic, are differentiated based on histology. Despite MC’s increasing incidence, understanding of the disease remains limited1. CASE DESCRIPTION/METHODS: A 67-year-old woman with hyperlipidemia on simvastatin and rectal prolapse status post rectopexy and sigmoidectomy 4 weeks prior presented with new diarrhea. She had up to 15 large, watery bowel movements per day, regardless of fasting or time of day. Stool studies were negative for infection. Physical exam had no prolapse. Past colonoscopies showed internal hemorrhoids, and recently resected colon specimen only had microscopic prolapse findings. Colonoscopy performed 3-months post-surgery showed healthy appearing mucosa, but biopsy revealed collagenous colitis (CC) (Fig. 1, 2). Budesonide was started for 8 weeks with dramatic clinical improvement. Simvastatin was stopped as possible trigger of CC. Her diarrhea recurred while tapering off budesonide, necessitating an extended course and slower taper. DISCUSSION: MC is a chronic inflammatory disease of unclear pathogenesis. Known risk factors include increasing age, female sex, and certain medications (NSAIDs, statins, proton-pump inhibitors).1 Though there is no known association between rectal prolapse or sigmoidectomy with development of MC, post-surgical changes in gut microbiota may have contributed (similar to dysbiosis implicated in inflammatory bowel disease).2 The treatment aim is to induce clinical remission. While steroid-sparing agents are available, budesonide is most effective.3 Patients with baseline higher stool frequency ( >5/day) have higher risk of symptom relapse with tapering budesonide, and may need long-term maintenance therapy.4Figure 1.: Trichrome stain of colon biopsy highlighting the subepithelial collagen deposition (blue).Figure 2.: Hematoxylin and eosin (H&E) stain of colon biopsy highlighting subepithelial collagen deposition (light pink).