S3880 Refractory Collagenous Colitis Requiring Inpatient Infliximab Infusion

Introduction: Microscopic colitis, which includes collagenous and lymphocytic colitis, is characterized by chronic watery diarrhea and diagnosed via biopsy. First line therapies such as budesonide are usually effective as the disease course is typically benign. Rarely, patients develop treatment-refractory disease requiring escalation of treatment beyond guideline-directed management. Limited studies have described the use of biologics for severe cases. We present a case of refractory collagenous colitis, highlighting the associated morbidity and the challenges in initiating infliximab. Case Description/Methods: A 44-year-old woman with celiac disease, recurrent Clostridioides difficile infections, 6-year history of collagenous colitis and protein-calorie malnutrition was hospitalized for profound hypokalemia, hyponatremia and hypophosphatemia identified on outpatient labs. She reported flares with nausea, vomiting and 6-10 episodes of non-bloody diarrhea daily every few months. Multiple therapies, including loperamide, diphenoxylate-atropine, budesonide, bismuth subsalicylate, cholestyramine, colesevelam, mesalamine, gluten-free diet, and recent initiation of prednisone with azathioprine for the current flare have been ineffective. Attempts to initiate outpatient biologic therapy, with infliximab or vedolizumab, were unsuccessful due to insurance denial. Repeat infectious workup and fecal calprotectin were negative and imaging showed diffuse enterocolitis. TPN was started and trials of octreotide and rifaximin yielded no improvement. Eventually, infliximab was administered inpatient due to failure of all prior therapies, persistent large-volume diarrhea and evidence of malabsorption. Normalization of C-reactive protein and improvement in stool output (<5 bowel movements daily) was observed after starting infliximab. Discussion: This case illustrates the challenges involved in the management of severe, refractory collagenous colitis. Severity and chronicity of microscopic colitis may mimic that of inflammatory bowel disease, and biologic therapy such as TNF-α inhibitors may be used for treatment, although current knowledge is based on case reports and studies. Further research is needed to investigate the role, safety and efficacy of biologics for treating microscopic colitis, which may help streamline off-label treatments, decrease morbidity, improve barriers for initiating such medications and resource utilization.