A curious case of diarrhea

77-year old woman presented with a two-month history of diarrhea. She had a past medical history of infectious colitis dating from 2005, including duodenitis with partial villous atrophy on duodenal biopsy. Celiac serology was negative at the time. Her medication included pantoprazole, aspirin, loop diuretic, statin, levothyroxin, angiotensin-converting-enzyme inhibitor (ACE-inhibitor), benzodiazepine and diltiazem. She reported smoking a few cigarettes a day. A colonoscopy was performed, which showed spontaneous mucosal tears with bleeding in the right colon (Fig. 1 : A-B). What is your diagnosis? A. Ischemic colitis B. Collagenous colitis C. Barotrauma secondary to insufflation during colonoscopy D. Ulcerative colitis The correct answer is B. The pathology report confirmed the presence of collagenous colitis (CC). Given the impressive presentation, the patient was started on budesonide, with complete resolution of the symptoms a few weeks later. A follow-up gastroscopy was performed to obtain new duodenal biopsies. These showed no signs of celiac disease. Pantoprazole was stopped, as the gastroscopy was normal, as were the statins. Budesonide was tapered over a 12-week period. She was also advised to quit smoking.