[Fatal infectious mononucleosis during azathioprine treatment in Crohn's disease].

The benefits of immunosuppressive agents in inflammatory bowel disease have been the subject of controversy. However, extensive clinical data have conclusively proved their efficacy with respect to potential toxicity. Azathioprine is one of the most widely used immunosuppressive agents in the treatment of Crohn's disease and its effectiveness has been proved in corticosteroid dependent, corticosteroid-refractory and fistulizing Crohn's disease. We present a 24-year-old male, treated with azathioprine for corticosteroid dependent Crohn's disease who was admitted to hospital with constant fever, lymphadenopathy and liver function abnormalities secondary to infectious mononucleosis after a primary infection with Epstein-Barr virus. The patient developed constitutional symptoms and progressive jaundice and 14 days after hospital admission died because of massive upper gastrointestinal bleeding due to hemorrhagic erosive gastropathy.