How does essential thrombocythemia fit in myeloproliferative disorders?
Thrombocythemia (or thrombocytosis) is defined as the occurrence of a platelet count in excess of 400,000 per microliter in the setting of a myeloproliferative disease. When this is the predominant abnormality, the syndrome is classified as essential thrombocythemia. Abnormal megakarocyte proliferation (platelet precursors) is seen in all variants of MPD and elevated platelet counts is common in PV, CML and the proliferative states of AMM. On the other hand, ET patients can also have elevated white cell count (WBC), hematocrit (HCT) and hemoglobin (HG) counts so a careful differential diagnosis is essential. 4.
