Table 4 Criteria for essential... | American Society of Hematology

Table 4

Criteria for essential thrombocythemia (ET)

Diagnosis requires meeting all 4 criteria
Sustained platelet count ≥ 450 × 10⁹/L* Bone marrow biopsy specimen showing proliferation mainly of the megakaryocytic lineage with increased numbers of enlarged, mature megakaryocytes. No significant increase or left-shift of neutrophil granulopoiesis or erythropoiesis. Not meeting WHO criteria for polycythemia vera,† primary myelofibrosis,‡BCR-ABL1–positive CML,§ or myelodysplastic syndrome,‖ or other myeloid neoplasm. Demonstration of JAK2 V617F or other clonal marker, or in the absence of JAK2 V617F, no evidence of reactive thrombocytosis¶.

Diagnosis requires meeting all 4 criteria

Sustained platelet count ≥ 450 × 10⁹/L*
Bone marrow biopsy specimen showing proliferation mainly of the megakaryocytic lineage with increased numbers of enlarged, mature megakaryocytes. No significant increase or left-shift of neutrophil granulopoiesis or erythropoiesis.
Not meeting WHO criteria for polycythemia vera,† primary myelofibrosis,‡BCR-ABL1–positive CML,§ or myelodysplastic syndrome,‖ or other myeloid neoplasm.
Demonstration of JAK2 V617F or other clonal marker, or in the absence of JAK2 V617F, no evidence of reactive thrombocytosis¶.

ET indicates essential thrombocythemia; BM, bone marrow; WHO, World Health Organization; and CML, chronic myelogenous leukemia.

Sustained during the work-up process.

†

Requires the failure of iron replacement therapy to increase hemoglobin level to the polycythemia vera range in the presence of decreased serum ferritin. Exclusion of polycythemia vera is based on hemoglobin and hematocrit levels, and red cell mass measurement is not required.

‡

Requires the absence of relevant reticulin fibrosis, collagen fibrosis, peripheral blood leukoerythroblastosis, or markedly hypercellular marrow accompanied by megakaryocyte morphology that is typical for primary myelofibrosis—small to large megakaryocytes with an aberrant nuclear/cytoplasmic ratio and hyperchromatic, bulbous, or irregularly folded nuclei and dense clustering.

Requires the absence of BCR-ABL1.

‖

Requires the absence of dyserythropoiesis and dysgranulopoiesis.

Causes of reactive thrombocytosis include iron deficiency, splenectomy, surgery, infection, inflammation, connective tissue disease, metastatic cancer, and lymphoproliferative disorders. However, the presence of a condition associated with reactive thrombocytosis does not exclude the possibility of ET if other criteria are met.

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