Acute blast crisis with EBV-infected blasts, in a patient with chronic myeloid leukemia, and vasculitis

Unless they undergo transplantation, all patients with chronic myeloid leuk emia (CML) will eventually develope a late phase of acute blast crisis (ABC ). Although additional chromosomal abnormalities to the Philadelphia (Ph) c hromosome may herald ABC in many CML cases, the mechanisms leading to this fatal event are obscure. Viral etiology, including the Epstein-Barr virus ( EBV) has never been implicated in the pathogenesis of ABC in CML. Iloprost is an analogue of epoprostenol (prostacyclin; PGI2) commonly used for the t reatment of peripheral vascular diseases and acts via inhibition of platele t activation, and by vasodilation. A case of ABC with blasts of undetermine d lineage showing EBV infection in a male patient with Ph positive CML is d escribed here. This unusual event developed during a course of treatment wi th the prostacyclin analogue, iloprost administered for vasculopathic leg u lcers. The proliferating blasts stained positively by immunohistochemistry only for the leukocyte common antigen (LCA/CD-45), and the EBV-latent membr ane protein 1 (LMP-I). The only chromosomal abnormality detected by cytogen etic analysis was the conventional Ph-chromosome. It is suggested that ABC in this case of CML, was associated with EBV-activated blasts of undetermin ed lineage.