Case Report: Acute Myeloblastic Leukemia Following Prolonged Treatment of Crohn's Disease with 6-Mercaptopurine

malignant cells revealed chromosome 7abnormalities, which are highly correlated with priorexposure to chemotherapy. Azathioprine and itsmetabolite 6-mercaptopurine (6-MP) have awell-established role in the treatment of inflammatory bowel disease(1-3). The reported occurrence of malignanciesassociated with prolonged use of these drugs for otherindications has tended to limit the duration of their use in patients with inflammatory bowel diseaseto one to two years. Studies have failed to showconvincing evidence of an increase in neoplasms amongpatients with inflammatory bowel disease attributable to these relatively short courses of therapy(4- 6). However, patients with refractory inflammatorybowel disease, especially Crohn's disease, are beingmaintained on immunosuppressants for longer periods of time with increasing frequency (3). Based onreports of neoplasia associated with chronicimmunosuppression for prevention of rejection of solidorgan transplants and for treatment of rheumatoidarthritis, there is concern that the incidence ofneoplasia will increase with longer durations ofimmunosuppressive therapy in inflammatory bowel disease.Nevertheless, a retrospective study did not reveal anydefinite correlation between 6-MP administration anddevelopment of neoplasms among 503 patients, 68% withCrohn's disease and 32% with ulcerative colitis, treatedfor a mean of 10 years (range: one week to more than 19 years) (7).