2016 WHO diagnostic criteria for ET compared with those for prefibrotic myelofibrosis
| Diagnostic criteria . | Major criteria . | Minor criteria . |
|---|---|---|
| For ET (Diagnosis of ET requires meeting all 4 major criteria or the first 3 major criteria and the minor criterion) | 1. PLT count ≥450 × 109/L 2. Bone marrow biopsy showing proliferation mainly of the megakaryocyte lineage with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei. No significant increase or left shift in neutrophil granulopoiesis or erythropoiesis and very rarely minor (grade 1) increase in reticulin fibers 3. Not meeting WHO criteria for BCR-ABL1+ chronic myeloid leukemia, PV, PMF, MDSs, or other myeloid neoplasms 4. Presence of JAK2, CALR, or MPL mutation | Presence of a clonal marker or absence of evidence for reactive thrombocytosis |
| For prefibrotic myelofibrosis (Diagnosis of prefibrotic myelofibrosis requires meeting all 3 major criteria, and at least 1 minor criterion) | 1. Megakaryocytic proliferation and atypia, without reticulin fibrosis >grade 1, accompanied by increased age-adjusted bone marrow cellularity, granulocytic proliferation, and often decreased erythropoiesis 2. Not meeting WHO criteria for BCR-ABL1+ chronic myeloid leukemia, PV, ET, MDSs, or other myeloid neoplasms 3. Presence of JAK2, CALR, or MPL mutation or in the absence of these mutations, presence of another clonal marker, or absence of minor reactive bone marrow reticulin fibrosis | Presence of at least 1 of the following, confirmed in 2 consecutive determinations: a. Anemia not attributed to a comorbid condition b. Leukocytosis (WBC count ≥11 × 109/L) c. Palpable splenomegaly d. Lactate dehydrogenase level increased to above upper normal limit of institutional reference range |
| Diagnostic criteria . | Major criteria . | Minor criteria . |
|---|---|---|
| For ET (Diagnosis of ET requires meeting all 4 major criteria or the first 3 major criteria and the minor criterion) | 1. PLT count ≥450 × 109/L 2. Bone marrow biopsy showing proliferation mainly of the megakaryocyte lineage with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei. No significant increase or left shift in neutrophil granulopoiesis or erythropoiesis and very rarely minor (grade 1) increase in reticulin fibers 3. Not meeting WHO criteria for BCR-ABL1+ chronic myeloid leukemia, PV, PMF, MDSs, or other myeloid neoplasms 4. Presence of JAK2, CALR, or MPL mutation | Presence of a clonal marker or absence of evidence for reactive thrombocytosis |
| For prefibrotic myelofibrosis (Diagnosis of prefibrotic myelofibrosis requires meeting all 3 major criteria, and at least 1 minor criterion) | 1. Megakaryocytic proliferation and atypia, without reticulin fibrosis >grade 1, accompanied by increased age-adjusted bone marrow cellularity, granulocytic proliferation, and often decreased erythropoiesis 2. Not meeting WHO criteria for BCR-ABL1+ chronic myeloid leukemia, PV, ET, MDSs, or other myeloid neoplasms 3. Presence of JAK2, CALR, or MPL mutation or in the absence of these mutations, presence of another clonal marker, or absence of minor reactive bone marrow reticulin fibrosis | Presence of at least 1 of the following, confirmed in 2 consecutive determinations: a. Anemia not attributed to a comorbid condition b. Leukocytosis (WBC count ≥11 × 109/L) c. Palpable splenomegaly d. Lactate dehydrogenase level increased to above upper normal limit of institutional reference range |
Information is from Arber et al.2