Related Subjects:
|Ulcerative Colitis
|Microscopic colitis
|Irritable bowel syndrome
|Lower Gastrointestinal (Rectal) Bleeding
💧 Microscopic Colitis = chronic, watery, non-bloody diarrhoea due to colonic inflammation only visible on biopsy.
👵 Typically affects older adults.
🌟 Unlike Crohn’s & UC, there is no increased colorectal cancer risk.
📖 About
- A subtype of IBD with normal macroscopic colonoscopy but diagnostic microscopic changes.
- Two main forms: Collagenous Colitis (CC) and Lymphocytic Colitis (LC).
- Distinct from Crohn’s/UC: no ulcers, strictures, or visible mucosal inflammation.
🔬 Types
- 🧱 Collagenous Colitis (CC): Thickened subepithelial collagen band + lamina propria inflammation.
- 🦠 Lymphocytic Colitis (LC): ↑ intraepithelial lymphocytes + lamina propria inflammation.
🤝 Associations
- 💊 Drugs: PPIs, NSAIDs, SSRIs, OCPs.
- 🚬 Smoking → ↑ risk (esp. collagenous colitis).
- Autoimmune overlap: coeliac disease, RA, type 1 diabetes.
- Bile acid malabsorption → worsens diarrhoea.
🩺 Clinical Presentation
- 💧 Chronic watery diarrhoea (non-bloody, persistent day & night).
- 🤕 Mild abdominal pain, cramping, bloating.
- ⚡ Urgency & incontinence common.
- +/- Nausea, fatigue, weight loss.
🔎 Investigations
- 📷 Colonoscopy: Appears normal → biopsy essential.
- 🔬 Histology:
– Collagenous: thickened collagen band.
– Lymphocytic: ↑ intraepithelial lymphocytes.
- 🧪 Barium enema: usually normal (not used in modern practice).
💊 Management
- 📋 Medication review: Stop triggers (NSAIDs, PPIs).
- 🥗 Lifestyle/diet: Reduce caffeine, fatty foods, lactose. Gluten-free diet in coeliac overlap.
- 💊 Symptomatic: Loperamide (Imodium), cholestyramine (if bile acid malabsorption).
- 🌟 First-line anti-inflammatory: Budesonide (effective, low systemic absorption).
- 🧪 Immunosuppressants: Azathioprine, methotrexate if refractory.
- 💉 Biologics: TNF inhibitors (Infliximab) for severe refractory cases.
- 🥤 Hydration & nutrition: essential for long-term symptom control.
📊 Prognosis
- Most achieve remission with budesonide ± lifestyle changes.
- Chronic relapsing course, but not progressive like Crohn’s/UC.
- ❌ No ↑ colorectal cancer risk → important distinguishing feature.
💡 Teaching Pearls:
– Think of microscopic colitis in 👵 older adults with chronic watery diarrhoea & normal colonoscopy.
– Always biopsy normal-looking colon if clinical suspicion.
– Budesonide = first-line therapy. Stopping culprit meds is often curative.
– Differentiating from IBS: nocturnal diarrhoea, weight loss, autoimmune associations = suggest pathology.
