Toxic megacolon developing in a patient with long-standing distal ulcerative colitis.

A young male with an eight-year history of stable distal ulcerative colitis acutely developed a toxic megacolon with mucosal involvement of the entire rectum and colon. This rare fulminant progression of previously stable disease underscores the lability of clinical severity of inflammatory bowel disease and the need to respond therapeutically to each recrudescence of symptoms on the basis of the severity of these symptoms and not the previously determined extent of colonic involvement.