Essential Thrombocythemia Followed by Acute Leukemia Does therapy lead to leukemic transition or is it a failure of accurate diagnosis? 63 yo male admitted with Appendicitis Diagnosed with Essential Thrombocythemia 1992. Treated with Chlorambucil to keep platelet count less than 600,000K 1999 diagnosed with AML; cytogenetics normal Offered induction therapy with 7+3. Pt refused. Continued on Chlorambucil. Stable AML x 2 years WS labs. WBC: 14.0, 45% Segs, 7% Bands, 15%Blasts Plts: 693K PCR for BCR/ABL + Objectives Establish the diagnostic criteria for Essential Thrombocythemia (ET) Discuss the natural history of ET Discuss the evidence supporting the treatment of ET Discuss acute Leukemia following ET Diagnostic Criteria for ET Platelet count 600,000 Hematocrit,40 or normal RBC mass Normal serum ferritin and MCV No Philadelphia Chromosome or bcr/abl gene rearrangement Absence of collagen Fibrosis on bone marrow No cytogenetic or morphologic evidence for a myelodysplastic syndrome No cause for reactive thrombocytosis Presenting Features Vasomotor symptoms...