Which of the following is the most common extraintestinal manifestation of inflammatory bowel disease?

Explanation

## Extraintestinal Manifestations of IBD **Key Point:** Erythema nodosum is the most frequent extraintestinal manifestation of IBD, occurring in 2–4% of patients with ulcerative colitis and 1–2% of those with Crohn's disease. ### Frequency Hierarchy | Manifestation | Frequency | Association | Notes | | --- | --- | --- | --- | | Erythema nodosum | 2–4% (UC), 1–2% (CD) | Both UC and CD | Most common; correlates with disease activity | | Arthralgia/arthritis | 1–2% | Both | Non-erosive, peripheral | | Aphthous ulcers | 0.5–1% | Both | Oral involvement | | Ankylosing spondylitis | 1–3% (HLA-B27+) | Both | HLA-B27 associated; independent of bowel activity | | Primary sclerosing cholangitis | 0.5–1.5% | Predominantly UC | Progressive; can occur without active colitis | | Pyoderma gangrenosum | 0.5–2% | Both (more UC) | Severe, necrotizing skin lesions | **High-Yield:** Erythema nodosum typically appears as painful, tender, red nodules on the shins and ankles. It correlates with active intestinal inflammation and usually improves with treatment of the underlying IBD. **Clinical Pearl:** While ankylosing spondylitis and primary sclerosing cholangitis are more specific to IBD (and carry worse prognosis), they are far less common than erythema nodosum. Erythema nodosum is the **most frequent** extraintestinal manifestation encountered in clinical practice. ### Why Erythema Nodosum Is Most Common 1. Immune-mediated hypersensitivity reaction to antigens (bacterial, dietary, or self-antigens) 2. Occurs in both UC and CD with similar relative frequency 3. Directly correlates with intestinal disease activity 4. Resolves with control of bowel inflammation **Mnemonic:** SEPIA — Skin (erythema nodosum), Eyes (uveitis), PSC, IBD, Arthritis. Skin manifestations (erythema nodosum) are the most common extraintestinal feature.