Copyright ©The Author(s) 2015.
World J Hematol. Aug 6, 2015; 4(3): 16-53
Published online Aug 6, 2015. doi: 10.5315/wjh.v4.i3.16
Table 8 2015 World Health Organization clinical molecular and pathobiological criteria for diagnosis of JAK2V617F mutated essential throbocythemia[77,78]
CM criteriaBone marrow pathology (P) criteria (WHO)
ETNormocellular ET
(1) Platelet count of > 350 × 109/L and the presence of large platelets in a blood smearProliferation and clustering of enlarged mature pleomorphic megakaryocytes with hyperlobulated nuclei and mature cytoplasm, lacking conspicuous morphological abnormalities
(2) Heterozygous JAK2V617F mutation, and low JAK2 allele mutation loadNormocellular bone marrow (< 60%) and no proliferation or immaturity of granulopoiesis or erythropoiesis
(3) Normal erythrocytes < 5.8 × 1012/L males, < 5.6 × 1012/L femalesRF 0 or 1
(4) Hb and ht normal or in the upper range of normal
Prodromal PVET with bone marrow features of PV
(1) Platelet count of > 350 × 109/L Hb and Ht normak or in the upper range of normal, normal erythrocyte < 5.8 × 1012/L males, < 5.6 × 1012/L femalesIncreased cellularity (60%-80%) due to increased erytropoiesis or trilineage myeloproliferation (i.e., panmyelosis). Proliferation and clustering of medium sized to large (pleomorphic) mature megakaryocytes
(2) Presence of JAK2V617F mutation and variable JAK mutation loadAbsence bone marrow features consistent with congenital polycythemia and secondary erythrocytosis
(3) Low serum EPO level and increased LAP scoreRF 0 or 1
(4) Spontaneous EEC
Prefibrotic hypercellular ETEMGM
(1) Platelet count of > 350 × 109/LHypercellular ET due to chronic megakaryocytic and EMGM and normal or reduced erythroid precursors
(2) Presence of JAK2V617F mutation and high JAK2 mutation loadLoose to dense clustering of more pleiomorphic megakaryocytes with hyperploid or clumpsy nuclei (not or some cloud-like)
(3) Slight or moderate splenomegaly on ultrasound or on palpation
(4) No preceding or allied CML, PV, PMGM, RARS-T or MDS
Clinical stage 1: No anemia with Hb and Ht in the normal or low normal range: hb > 12 g/dL, normal LDH and CD34+Grading of reticulin fibrosis and MF in EMGM
Clinical stage 2: Slight anemia Hb < 12 to > 10 g/dL, LDH↑, and splenomegalyPrefibrotic: RF 0/1 = MF 0, no/minor splenomegaly
Clinical stage 3: Anemia, Hb < 10 g/dL, LDH↑↑, CD34+, leukoerythroblastose and, tear dropEarly fibrotic EMGM: RF 2 = MF 1 and minor or moderate splenomegaly
Fibrotic EMGM: RF 3, RCF = MF 2 and overt splenomegaly
Post-ET MF: RF 3/4 = MF 2/3 (WHO criteria)