Acute promyelocytic leukemia developing in untreated essential thrombocythemia

We describe a patient with untreated essential thrombocythemia (ET) who developed microgranular variant of acute promyelocytic leukemia, 9 years after the initial diagnosis of ET. He achieved complete remission (CR) but relapsed 11 months later. After achieving the second CR, he received peripheral stem cell transplantation from his HLA complete-matched sibling. Five months after the transplantation, he relapsed again with meningeal infiltration of leukemic cells. In this paper, we review cases of promyelocytic transformation of myeloproliferative diseases (MPD) other than chronic myeloid leukemia (CML). To our knowledge, this is the first case of promyelocytic transformation of Philadelphia chromosome negative untreated ET, in whom both t (15;17) and PML-RAR fusion were proven. Am. J. Hematol. 71:114-116, 2002.