Collagenous Colitis: Rare Case of Seasonal and Environmental Exacerbation of Collagenous Colitis Responding to Montelukast

Abstract

Purpose: Background: Collagenous colitis (CC) is a cause of chronic diarrhea characterized by grossly normal mucosa and a sub-epithelial band of collagen. We report a case of CC showing an exacerbation pattern to environmental change and an excellent response to treatment with montelukast in the setting of biopsy proven CC with increased submucosal eosinophils. Case: A 70 year old relatively healthy white male with a baseline history of allergic rhinitis presented with a three month history of profuse watery diarrhea. Colon biopsy revealed CC. He responded to pepto-bismol and two years later to asacol on such an exacerbation. A year later he developed refractory diarrhea to Pepto-Bismol, loperemide, asacol, cholestyramine and he refused steroids. Colon biopsy revealed CC with increased eosinophils. WBC count was normal with a normal differential and normal ESR. Stool microscopy and serology was negative for Giardia, Cryptospora, Salmonella, Shigella, E. coli O157 and Clostridium difficile toxin. Serum IgA, tissue trans-glutaminase, IBD-7panel and liver function panel were unremarkable. Skin testing for an extensive food panel was unrevealing. The diarrhea responded well to a cromolyn taper and continual montelukast therapy. Thereafter, episodes of diarrhea recurred each time montelukast was stopped. One year post montelukast treatment colon biopsy revealed decreased number of eosinophils with a persistent collagen band. Interestingly, this patient would have no recurrences in winter when he vacationed in Florida prior to starting montelukast. Discussion: The seasonal pattern of his symptoms occurring in summer in Rochester, New York and resolution of diarrhea from his Florida vacation in winter may suggest an unknown environmental allergen or an infectious etiology. The pathogenesis may be similar to sub-epithelial fibrosis caused in irritant induced asthma (irla) by eosinophil induced inflammation. Colon perfusion models in CC and bronchial washings in irla show increased eosinophilic cationic protein, fibroblast growth factor. Interestingly, CC reverses completely with diverting ileostomies, pointing to luminal factors causing CC. This patient's sustained response to treatment with montelukast may be explained by the fact that montelukast decreases the levels of inducible nitric oxide synthase (iNOS) and may alter eosinophil adhesion as shown in experimental models. Conclusion: The etiology of CC is speculative. CC may respond to montelukast therapy in steroid resistant/averse patients especially in the setting of increased eosinophils on histology and patients having other systemic allergy symptoms. Well powered studies are necessary to compare it head-on to budesonide.