Table 1 Essential Thrombocythemia (ET) starting with a high threshold level of sustained platelet count (WHO refs. # [4,5,6,7] versus ICC ref.# [14]).
Year Major criteria | 2001 Jaffe ES et al. ref. # [4] | 2008 Swerdlow SH et al. ref. # [5] | 2017 Swerdlow SH et al. ref. # [6] | 2024 Akkari Y et al. ref.# [7] | 2022 Arber DA. et al. ref. # [14] |
|---|---|---|---|---|---|
Platelet count | ≥ 600 x109/L | ≥ 450 x109/L | ≥ 450 x109/L | ≥ 450 x109/L | ≥ 450 x109/L |
Bone marrow morphology | Bone marrow biopsy specimen showing proliferation mainly of the megakaryocytic lineage with increased numbers of enlarged, mature megakaryocytes | 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 neutrophilic granulopoiesis or erythropoiesis | Bone marrow biopsy showing proliferation mainly of the megakaryocytic lineage, with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei; no significant increase or left shift in neutrophilic granulopoiesis or erythropoiesis; very rarely a minor (grade 1) increase in reticulin fibers | Bone marrow biopsy showing proliferation mainly of the megakaryocytic lineage, with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei; no significant increase or left shift in neutrophilic granulopoiesis or erythropoiesis; very rarely a minor (grade 1) increase in reticulin fibers | Bone marrow biopsy showing proliferation mainly of the megakaryocytic lineage, with increased numbers of enlarged, mature megakaryocytes with hyperlobulated staghorn-like nuclei, infrequently dense clusters; no significant increase or left shift in neutrophil granulopoiesis or erythropoiesis; no relevant BM fibrosis |
Criteria of Exclusion | No evidence of PV, CML, PMF, MDS; no evidence for reactive thrombocytosis | Not meeting WHO criteria for PV, PMF, BCR::ABL1 positive CML, MDS or other myeloid neoplasm | WHO criteria for BCR::ABL1 positive chronic myeloid leukemia, polycythemia vera, primary myelofibrosis or other myeloid neoplasms are not met | WHO criteria for BCR::ABL1 positive chronic myeloid leukemia, polycythemia vera, primary myelofibrosis or other myeloid neoplasms are not met | Diagnostic criteria for BCR::ABL1 positive CML, PV, PMF, or other myeloid neoplasms are not met |
Clonal genetic abnormality | Demonstration of JAK2 V617F or other clonal marker, or in the absence of JAK2 V617F, no evidence for reactive thrombocytosis | JAK2, CALR, or MPL mutation | JAK2, CALR, or MPL mutation | JAK2, CALR, or MPL mutation | |
Minor Criteria | Presence of a clonal marker or absence of evidence of reactive thrombocytosis | 1. Presence of a clonal marker or 2. Exclusion of reactive thrombocytosis | Presence of a clonal marker or absence of evidence of reactive thrombocytosis | ||
Diagnosis requires meeting criteria 1 and 2 and criteria of exclusion | Diagnosis requires meeting all four criteria | The diagnosis of essential thrombocythemia requires that either all major criteria or the first 3 major criteria plus the minor criterion are met | The diagnosis of essential thrombocythemia requires that either all major criteria or the first 3 major criteria plus the minor criterion are met | The diagnosis of ET requires either all major criteria or the first 3 major criteria plus the minor criteria |
