Crohn's disease and its mucocutaneous involvement.

Crohn's disease (CD) is a chronic inflammatory disorder primarily affecting the lower gastrointestinal tract but potentially involving the skin, musculoskeletal system, and eyes. The origin remains unknown, although diverse etiologic agents have been proposed. Characteristic pathologic appearances include the formation of "skip" lesions (discrete regions of inflamed bowel separated by uninvolved mucosae), aphthous ulceration, and fistulation; these signs relate to the presence of an underlying granulomatous transmural inflammation. Cutaneous and oral lesions frequently occur in CD. They may be classified as specific manifestations (in particular, perianal fissures, abscesses, sinuses, and fistulae in ano) with a granulomatous noncaseating inflammation on histologic examination, and nonspecific manifestations (eg, erythema nodosum, neutrophilic dermatoses) with a nonspecific histologic pattern. The diagnosis of CD is based on clinical, endoscopic, radiologic, and histopathologic features. Therapy is mainly aimed at the control of the acute disease and prevention of relapse through the use of mesalazine, corticosteroids, immunosuppressive agents and very recently, anti-tumor necrosis factor-alpha antibodies.