Crohn's Disease

The causes are still not fully understood. Crohn's disease is thought to result from an inappropriate immune response in genetically predisposed people, due to a complex interaction between environmental factors, microbes and the intestinal immune system.

Crohn's disease is a transmural inflammatory disease (affecting the full thickness of the bowel wall) that can affect the entire digestive tract, from the mouth to the anus. Extra-digestive manifestations include: uveitis, mouth ulcers, arthritis and polyarthritis, erythema nodosum, and primary sclerosing cholangitis.

The diagnosis should be considered in any chronic diarrhea associated with abdominal pain. General symptoms (fever, loss of appetite, weight loss, general fatigue) are often present. Symptoms vary depending on location: ileal and ileocecal forms (pain in the lower right abdomen and moderate watery diarrhea), left-sided colonic or pancolonic forms (diffuse pain and diarrhea with mucus and blood), and stricturing forms (Koenig syndrome). Anal and perineal manifestations can be pronounced: fistulas, abscesses, strictures.

Endoscopic examinations (upper GI endoscopy, colonoscopy, enteroscopy, capsule endoscopy) are essential to see the lesions of the digestive tract and, above all, to take biopsies. The histological finding specific to Crohn's disease is the epithelioid granuloma.

Crohn's disease progresses in flare-ups separated by periods of remission, either spontaneous or induced by treatment. Taking NSAIDs is the only identified factor that triggers flare-ups; quitting smoking reduces their frequency. About 70% of patients will need surgery during their lifetime.

Medical treatment includes several therapies:

• Salicylates (very limited or no role)
• Systemic corticosteroids
• Immunosuppressants: azathioprine, 6-mercaptopurine
• Anti-TNF agents: infliximab, adalimumab…
• More recently: vedolizumab, ustekinumab

Surgery should be avoided as much as possible and, in all cases, be as conservative as possible (shortest possible resection of the affected segment).