Chronic myeloid leukemia in an ulcerative colitis patient receiving azathioprine: A case report.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease usually treated by azathioprine. It is a well-established risk factor for colorectal cancers and extraintestinal malignancies. Nevertheless, the risk of myeloid leukemia in patients with UC is less known. We report a case of a 51-year-old patient, with a history of extensive ulcerative colitis, who was treated with azathioprine at a dose of 2.5 mg/kg/day. Seven years later, he presented an increased count of white blood cells at 25,400/μL and of platelets at 1,382,000/μL. Peripheral blood smear showed 1% blasts and 20% myelemia. The karyotype showed the Philadelphia chromosome and the RT-PCR revealed the BCR-ABL transcript. Thus, chronic myeloid leukemia (CML) was confirmed and imatinib was prescribed. This case reported a rare and serious event in a UC patient and illustrates the importance of closely monitoring this population.