What are the key diagnostic criteria for microscopic colitis in adults presenting with chronic diarrhea?

The key diagnostic criteria for microscopic colitis in adults presenting with chronic diarrhea include:

• Chronic, non-bloody watery diarrhea persisting for weeks to months, often without systemic symptoms such as weight loss or fever, is the typical clinical presentation ¹ (Münch and Langner, 2015).
• Colonoscopy findings are usually normal or show minimal mucosal changes,1 (Zabana et al., 2017).
• Histological examination of colonic biopsies is essential,10 µm) with increased intraepithelial lymphocytes for collagenous colitis, or increased intraepithelial lymphocytes (>20 per 100 epithelial cells) without collagen band thickening for lymphocytic colitis (Münch and Langner, 2015; Pardi, 2017).
• Exclusion of other causes of chronic diarrhea,1 (Pardi, 2017).
• Multiple biopsies from different colonic segments, including the right and left colon,

In summary, the diagnosis relies on clinical suspicion in adults with chronic watery diarrhea, normal endoscopic appearance, and confirmatory histopathology showing either collagenous or lymphocytic colitis patterns. This integrated approach from UK guidelines and recent literature ensures accurate diagnosis and appropriate management ¹ (Münch and Langner, 2015; Zabana et al., 2017; Pardi, 2017).