Crohn 's disease is often associated with manifestations at sites separate and distinct from the gastrointestinal tract (1-3). The presence of these "extraintestinal" manifestations suggests that Crohn 's disease may be a systemic disorder in which the gastrointestinal tract is the predominant but not the only organ involved. The extraintestinal manifestations that are associated with Crohn 's disease can occasionally overshadow and may sometimes be more devastating to the patient's quality of life than the underlying bowel disease. This chapter reviews the extraintestinal manifestations of Crohn 's disease, describes their relationship to the location and activity of intestinal inflammation, discusses therapy, and differentiates between extraintestinal manifestations of Crohn's disease and those that are direct complications of the underlying bowel disease. Most of the extraintestinal manifestations reviewed in this chapter can also be seen in association with ulcerative colitis. Therefore, issues that are relevant to extraintestinal manifestations in ulcerative colitis are also reviewed
A. Aseptic Neutrophilic Dermatosis The mucocutaneous abnormalities that accompany inflammatory bowel disease (ffiD) can be viewed as a spectrum of changes resulting from leukocyte migration to different sites in the skin and mucous membranes (4,5). Pyostomatitis vegetans, psoriasis, vesicul<>- pustular eruptions, epidermolysis bullosa acquisita, Sweet's syndrome, erythema nodosum, and pyoderma gangrenosum can all be considered various forms of an aseptic neuttophilic dermatosis. These same mucocutaneous changes can also be seen in other intestinal/ multisystem disorders, such as Be~et's disease, Reiter's syndrome, infectious enterocolitis, bowel-associated dermatosis-arthritis syndrome, and collagen vascular disorders (rheumatoid arthritis and systemic lupus erythematosus, in particular).