Ulcerative colitis and rheumatoid arthritis: a rare association--case report.

Ulcerative colitis is an autoimmune disorder of unknown etiology. Although the large intestine is the major focus of autoimmunity, resulting in chronic diarrhea, that is actually a systemic disease, with numerous extraintestinal manifestations, such as articular involvement. The frequent association of a number of autoimmune diseases in the same patient has been described.