Cutaneous Manifestations of Inflammatory Bowel Disease: A Basic Overview.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal (GI) tract that is subdivided into Crohn's disease (CD) and ulcerative colitis (UC). CD is characterized by involvement of the entire GI tract, while UC mainly affects the distal GI tract. Moreover, both CD and UC can present with extraintestinal manifestations (EIMs) of the disease affecting multiple organ systems including the hepatobiliary tract, kidney, bones, eyes, joints, and skin. These complications can cause significant morbidity and negatively impact the quality of life for IBD patients. Although the pathogenesis of EIMs is not clearly elucidated, it is postulated that the diseased GI mucosa similarly stimulates excess immune responses at the extraintestinal sites. Cutaneous EIMs occur in up to 15% of patients with IBD, often predating their IBD diagnosis. They are categorized into (1) specific, (2) reactive, (3) associated, and (4) treatment-induced. Here, we review the epidemiological, clinical, diagnostic, and histologic features of the most commonly described cutaneous EIMs of IBD along with their respective treatment options.