IBD Extraintestinal Manifestations
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Direct answer
IBD extraintestinal manifestations are immune-mediated features outside the gut, affecting the skin, joints, eyes and liver. Some follow bowel activity, including type 1 peripheral arthritis, erythema nodosum, episcleritis and aphthous ulcers. Others run independently of the bowel, most notably axial spondyloarthropathy, type 2 polyarthritis, uveitis, pyoderma gangrenosum and primary sclerosing cholangitis, which is strongly linked to ulcerative colitis.
What you must remember
- Type 1 peripheral arthritis: pauciarticular, affecting a few large joints such as the knee, and it parallels bowel activity.
- Type 2 peripheral arthritis: polyarticular, affecting five or more small joints, and it runs independently of bowel activity.
- Axial disease: sacroiliitis or ankylosing spondylitis causing inflammatory back pain, which runs independently of bowel activity and is linked to HLA-B27.
- Erythema nodosum: tender red nodules on the shins that track bowel activity and settle with control of the colitis or Crohn disease.
- Pyoderma gangrenosum: painful ulcer with an undermined violaceous edge, whose course is often independent of bowel activity.
- Eye features: episcleritis tracks activity, whereas anterior uveitis runs independently and needs urgent ophthalmology review and topical steroids.
- Primary sclerosing cholangitis: strongly linked to ulcerative colitis and progresses regardless of colitis activity, with a raised cholangiocarcinoma risk.
- Thromboembolism: venous thrombosis risk rises during active disease and hospitalisation, so prophylaxis is considered.
A stepwise approach to a new joint or skin lesion
A 29-year-old man with known Crohn disease develops painful red shin nodules during a flare, and a knee effusion appears a week later. The question is which features will settle with bowel control and which need their own treatment.
- Match the feature to activity: Ask whether the lesion appeared with a flare, since activity-linked features usually settle when the bowel is controlled.
- Examine the joint pattern: Type 1 peripheral arthritis involves a few large joints, whereas type 2 involves many small joints and axial disease causes inflammatory back pain with sacroiliac tenderness.
- Check the liver tests: A cholestatic pattern with raised alkaline phosphatase and gamma-GT calls for MRCP to look for sclerosing cholangitis.
- Treat the bowel first: Controlling the underlying inflammation usually resolves the activity-linked features, often with steroids or a biologic.
- Treat the eye or skin directly: Topical steroids are used for episcleritis, and specialist care is needed for uveitis and pyoderma gangrenosum.
- Review the drugs: NSAIDs can precipitate flares, so they are avoided, and sulfasalazine is a useful option for peripheral arthritis.
Where the exam tests the extraintestinal trap
The commonest errors involve a feature that seems to belong to the gut but does not.
- Trap: assuming every joint pain tracks gut activity Correct: axial disease and type 2 small-joint arthritis run independently, and axial disease may need a specific biologic such as an anti-TNF agent.
- Trap: attributing raised alkaline phosphatase to stones alone Correct: in ulcerative colitis, primary sclerosing cholangitis must be excluded with MRCP.
- Trap: giving NSAIDs for IBD-related arthritis Correct: NSAIDs can trigger flares, so they are avoided where possible.
Frequently asked questions
Which IBD extraintestinal features track bowel disease activity?
Type 1 peripheral arthritis, erythema nodosum, episcleritis and aphthous stomatitis track IBD activity and usually settle with control of the bowel. Type 1 peripheral arthritis is the main joint example, affecting a few large joints in parallel with the colitis or Crohn disease.
Which IBD extraintestinal manifestation runs independently of bowel activity?
Axial spondyloarthropathy, including sacroiliitis and ankylosing spondylitis, runs independently of bowel activity and is linked to HLA-B27. Pyoderma gangrenosum, uveitis, type 2 polyarthritis and primary sclerosing cholangitis also run largely independently. Inflammatory back pain may need separate treatment, such as an anti-TNF agent, when conventional therapy fails.
Why must primary sclerosing cholangitis be considered in ulcerative colitis?
Primary sclerosing cholangitis is strongly associated with ulcerative colitis and can progress regardless of colitis activity. A raised alkaline phosphatase in such a patient should prompt MRCP to look for bile duct changes, since cholangiocarcinoma risk is also raised.
Why are NSAIDs avoided in inflammatory bowel disease?
NSAIDs can precipitate or worsen flares of inflammatory bowel disease, so they are generally avoided in patients with active disease. Paracetamol is preferred for pain, and any NSAID use should be discussed with the gastroenterology team first.