Essential thrombocythemia transformed to acute myelogenous leukemia with t(3;17)(p24;q12), del(5)(q13q34) after treatment with carboquone and hydroxyurea

In 1991, a 52-year-old woman was diagnosed as having essential thrombocythe mia (ET). She was doing well with continuous medication with carboquone (CQ ) and subsequently hydroxyurea (HU). However, substantial leukocytosis with leukemic blast cells, anemia and thrombocytopenia developed in 1996. Analy sis of peripheral blood showed 4.4 x 10(3)/mu l white blood cells with 82% of leukemic blast cells. These blasts showed negative staining with myelope roxidase by immunostaining, but the myeloperoxidase was positive by electro n microscopic analysis. Cytogenetic analysis of bone marrow cells revealed a t(3;17)(p24;q12), del(5)(q13q34), On the basis of these findings, the leu kemic blast cells were classified as acute myelogenous leukemia (AML:M-0) i n the FAB classification. The causative agent, CQ and HU in secondary leuke mia from ET and chromosomal abnormality related to ET blastic crisis (BC) a re discussed.