single manifestation of Crohn’s Disease

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Crohn’s disease is most common in the developed countries and has a bimodal age distribution. The peak incidence is between the ages of 15 and 25 years with a lower peak between 50 and 80 years. Crohn's disease can involve any segment of the alimentary tract. However, the terminal ileum is nearly always involved in small bowel disease and is the only site in up 30% of patients. Only 15% of the cases of Crohn's disease appear in patients older than 50 years. The radiographic manifestations of Crohn's disease are well known and include thickened folds, nodules and aphtous ulcers, fissures and linear, deep ulcers, “cobblestoning”, sacculation of antimesenteric aspect, limited distensibility with thickening of walls, inflammatory pseudopolyps, sinus tracts and fistulae and narrowed lumen (“string sign”) (1). CT features are bowel wall thickening (usually between 1-2 cm), mural stratification giving a target or double-halo appearance and intense mucosal and serosal enhancement following IV contrast, in the acute phase. In chronic disease, mural stratification is lost as transmural fibrosis is established (2). Mesenteric changes include fibro-fatty proliferation, increased attenuation, small lymph nodes and hypervascularity giving a “comb sign”. CT is also valuable because of its ability in depicting extraluminal pathology (3). Strictures occur in 20% of patients with small bowel disease and 8% of patients with Crohn´s colitis. In the active stage of the disease the narrowing usually results from edema and spasm and is not permanent. In long-standing disease, fibrotic strictures predominate. Other complications are abscesses, fistulae formation, perforation and GI as well as extra-GI cancer.