SARS-CoV-2-triggered lymphocytic colitis

The ability of SARS-CoV-2 to infect the gastrointestinal tract is well described. Inflammatory bowel diseases (IBD) are believed to represent a disorganised immune response in genetically predisposed individuals, which are triggered by various environmental factors, notably infections. Here we report a case of chronic watery diarrhoea that was triggered by a SARS-CoV-2 infection. The work-up confirmed a new diagnosis of lymphocytic colitis, and the patient responded favourably to a course of oral budesonide. Clinicians should become vigilant to the possibility of triggered IBD in patients with persistent diarrhoea following a SARS-CoV-2 infection.

A196 MORE MICROSCOPIC THAN WAS THOUGHT: A RARE CASE OF ISOLATED LYMPHOCYTIC ILEITIS WITHOUT MICROSCOPIC COLITIS

Background Microscopic colitis (MC) is a chronic inflammatory disease of the colon characterized by lymphocytic infiltration with (collagenous colitis) or without (lymphocytic colitis) the expansion of collagen fibres, and the normal macroscopic appearance of the mucosa on ileocolonoscopy. Recent studies have shown that the ileum may be involved in MC, occurring concurrently with colonic disease, however there is sparse literature on isolated lymphocytic ileitis without colitis. Aims We describe the case of isolated small bowel lymphocytosis without evidence of lymphocytic colitis to highlight the utility of random biopsies of the terminal ileum in cases where microscopic colitis is a diagnostic consideration. Methods A 70-year-old female known for cutaneous mastocytosis presented with six weeks of abdominal pain, non-bloody diarrhea, intolerance to oral intake and significant weight loss. Computed-tomography showed evidence of possible mesenteric panniculitis. Colonoscopy revealed a normal colon and normal-appearing mucosa of the terminal ileum. Random mucosal biopsies were taken to assess for microscopic colitis, with terminal ileal biopsies revealing significant lymphocytic infiltration consistent with lymphocytic ileitis. Biopsies throughout the colon revealed normal colonic mucosa without evidence of concurrent microscopic colitis. Gastroscopy was macroscopically unremarkable and random biopsies in the stomach and duodenum were negative for Helicobacter pylori and lymphocytosis. Immunostaining of the gastric, duodenal, terminal ileal and colonic biopsy specimens were negative for CD25, CD117 and tryptase, indicating the absence of gastrointestinal mastocytosis. Results The patient was diagnosed with lymphocytic ileitis and given the known response of MC to budesonide, she was treated with eight weeks of budesonide with clinical improvement leading to remission of her symptoms. Conclusions This case illustrates a rare incidence of isolated ileal microscopic ileitis without colitis that responded well to standard MC treatment, thereby underscoring the utility of random biopsies in the terminal ileum and throughout the colon when microscopic colitis is on the differential diagnosis. Funding Agencies None