Diagnostic criteria for ET according to the WHO, the International Consensus Classification, and the British Society for Haematology
| WHO fifth edition . | ICC 2022 . | BSH (2014 modification of 2010 criteria) . | |||
|---|---|---|---|---|---|
| Major | Platelet count ≥450 × 109/L | Major | Platelet count ≥450 × 109/L | A1 | Sustained platelet count ≥450 × 109/L |
| 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 neutrophil granulopoiesis or erythropoiesis; very rarely a minor (grade 1) increase in reticulin fibers | Bone marrow biopsy showing proliferation mainly of megakaryocytes, 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 | A2 | Acquired pathogenic mutation (JAK2/CALR/MPL) | ||
| Diagnostic criteria for BCR::ABL1-positive CML, PV, PMF, or other myeloid neoplasms not met | Diagnostic criteria for BCR::ABL1-positive CML, PV, PMF, or other myeloid neoplasms not met | A3 | No other myeloid malignancy, especially PV, PMF, CML, or MDS | ||
| Presence of JAK2, CALR, or MPL mutation | Presence of JAK2, CALR, or MPL mutation | A4 | No reactive cause for thrombocytosis & normal iron stores | ||
| Minor | Presence of a clonal marker | Minor | Presence of a clonal marker | A5 | BM aspirate & trephine biopsy showing increased megakaryocyte numbers displaying a spectrum of morphology with predominant large megakaryocytes with hyperlobated nuclei and abundant cytoplasm. Reticulin generally not increased (grades 0-2/4 or grade 0/3) |
| or | or | ||||
| Exclusion of reactive thrombocytosis | Absence of evidence of reactive thrombocytosis | ||||
| Diagnosis requires either all major criteria or first 3 major criteria + minor criteria | Diagnosis requires either all major criteria or first 3 major criteria + minor criteria | Diagnosis requires A1-A3 or A1 + A3-A5 | |||
| WHO fifth edition . | ICC 2022 . | BSH (2014 modification of 2010 criteria) . | |||
|---|---|---|---|---|---|
| Major | Platelet count ≥450 × 109/L | Major | Platelet count ≥450 × 109/L | A1 | Sustained platelet count ≥450 × 109/L |
| 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 neutrophil granulopoiesis or erythropoiesis; very rarely a minor (grade 1) increase in reticulin fibers | Bone marrow biopsy showing proliferation mainly of megakaryocytes, 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 | A2 | Acquired pathogenic mutation (JAK2/CALR/MPL) | ||
| Diagnostic criteria for BCR::ABL1-positive CML, PV, PMF, or other myeloid neoplasms not met | Diagnostic criteria for BCR::ABL1-positive CML, PV, PMF, or other myeloid neoplasms not met | A3 | No other myeloid malignancy, especially PV, PMF, CML, or MDS | ||
| Presence of JAK2, CALR, or MPL mutation | Presence of JAK2, CALR, or MPL mutation | A4 | No reactive cause for thrombocytosis & normal iron stores | ||
| Minor | Presence of a clonal marker | Minor | Presence of a clonal marker | A5 | BM aspirate & trephine biopsy showing increased megakaryocyte numbers displaying a spectrum of morphology with predominant large megakaryocytes with hyperlobated nuclei and abundant cytoplasm. Reticulin generally not increased (grades 0-2/4 or grade 0/3) |
| or | or | ||||
| Exclusion of reactive thrombocytosis | Absence of evidence of reactive thrombocytosis | ||||
| Diagnosis requires either all major criteria or first 3 major criteria + minor criteria | Diagnosis requires either all major criteria or first 3 major criteria + minor criteria | Diagnosis requires A1-A3 or A1 + A3-A5 | |||
CML, chronic myeloid leukemia; BM, bone marrow; BSH, British Society for Haematology; ICC, International Consensus Classification; PMF, primary myelofibrosis; WHO, World Health Organization.