What are the key diagnostic criteria for microscopic colitis in adults

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 NICE NG130 Münch & Langner 2015.
• Colonoscopy findings are usually normal or show minimal mucosal changes,</strong necessitating biopsy for diagnosis NICE NG130 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 & Langner 2015Pardi 2017.
• Exclusion of other causes of chronic diarrhea,</strong including infections, inflammatory bowel disease, and malabsorption syndromes, is necessary before confirming microscopic colitis NICE NG130 Pardi 2017.
• Multiple biopsies from different colonic segments, including the right and left colon,</strong improve diagnostic yield as microscopic changes may be patchy Zabana et al. 2017.

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 NICE NG130 Münch & Langner 2015Zabana et al. 2017Pardi 2017.