Toxic megacolon associated with methotrexate therapy.

We describe the case of a patient with psoriasis who developed severe colitis, with toxic megacolon, after a course of treatment with methotrexate. The duration of her colitis, which was eventually resolved by using conservative measures, was far greater than that of other drug-related complications, which included bone marrow depression, jaundice, and renal failure. The literature pertaining to this rare manifestation of methotrexate toxicity is reviewed. A prolonged illness and relative sparing of the distal colon appear to be characteristic of this form of colitis.