Microscopic Colitis as a Cause of Chronic Diarrhea: Case Series and Literature Review

Abstract

Collagenous colitis (CC) is a subtype of microscopic colitis (MC) characterized by chronic watery, non-bloody diarrhea and specific histopathological findings. Once considered rare, it has recently gained recognition as an important cause of chronic diarrhea. We report a series of seven cases diagnosed in Tuxtla Gutiérrez, Chiapas, in patients presenting with chronic diarrhea lasting more than four weeks. Colonoscopy findings were unremarkable in all cases; diagnosis was established through colonic biopsies showing subepithelial collagen band thickening associated with inflammatory infiltrates. Infectious and metabolic causes were ruled out. Treatment consisted mainly of budesonide, with favorable clinical response and a significant reduction in stool frequency. In some patients, discontinuation of potentially associated medications was also indicated. This case series highlights CC as a growing cause of chronic diarrhea in our region and emphasizes the importance of including it in the differential diagnosis of chronic non-bloody diarrhea. Early recognition and adequate treatment improve patient outcomes and reduce unnecessary diagnostic procedures.