Perth Haematology :: Dr Steven Ward
Essential Thrombocytosis (ET)
ET is sometime also called Essential Thrombocythaemia.
ET is due to the primary overproduction of marrow platelets by their precursor cell, the megakaryocyte.
An elevated platelet count can be:
Revised WHO Diagnostic Criteria for ET
Diagnosis requires all 4 criteria
1. Sustained platelet count >= 450 x 109/L
2. BM biopsy showing proliferation mainly of the megakaryocytic lineage with increased numbers of enlarged, mature forms; no significant increase or left-shift of neutrophil granulopoisis or erythropoiesis.
3. Not meeting WHO criteria for PRV, MF, CML, MDS or other myeloid neoplasia.
4. Demonstration of JAK2 2617V>F or other clonal marker, or in the absence of a clonal marker no evidence for reactive thrombocytosis.
Features of ET