Crohn

Crohn's disease, commonly called Crohn disease, is a type of inflammatory bowel disease (IBD) featuring chronic, transmural inflammation that can affect any part of the gastrointestinal tract, most often the terminal ileum and colon. It was described by Burrill B. Crohn in 1932. The cause is not fully understood, but it is believed to involve an abnormal immune response to intestinal microbes in genetically susceptible individuals, influenced by environmental factors. The disease often follows a relapsing-remitting course.

Symptoms include abdominal pain, usually in the lower abdomen; persistent diarrhea; weight loss; fatigue; and sometimes blood in the stool. Perianal disease, fistulas, and strictures may occur. Extraintestinal manifestations can affect the skin, joints, and eyes.

Diagnosis depends on clinical evaluation, endoscopy with biopsy, and imaging such as MR enterography or CT enterography. Lab tests may show elevated inflammatory markers and anemia; fecal calprotectin helps distinguish IBD from infection. The pattern of skip lesions and transmural inflammation supports the diagnosis; granulomas may be present on biopsy but are not required.

There is no cure, but treatments aim to induce and maintain remission and prevent complications. Nutritional support and smoking cessation are important. Medications include aminosalicylates for mild disease, corticosteroids for flares, immunomodulators (azathioprine, methotrexate), and biologics (anti-TNF agents like infliximab or adalimumab; anti-integrin vedolizumab; ustekinumab). Antibiotics may be used for certain complications. Surgery may be necessary for obstruction, fistulas, or refractory disease; it alleviates symptoms but does not cure the condition.