PVSG and WHO vs European Clinical, Molecular and Pathological Criteria for prefibrotic myeloproliferative neoplasms

Table 4 World Health Organization and European Clinical, Molecular and Pathological criteria for diagnosis and staging of primary megakaryocytic granulocytic myeloproliferation, or primary myelofibrosis

Michiels JJ	Clinical criteria (2005)	Thiele J	pathological criteria (2005/2008)
A1	Hypercellular JAK2/MPL wild type ET and no preceding or allied other subtype of myeloproliferative neoplasm: JAK2V617F or MPL515 normocellular ET, prodromal or classical PV, Ph1+ CML or MDS	B1	PMGM and relative reduction of erythroid precursors. Abnormal clustering and increase in atypical giant to medium sized dysmorphic megakaryocytes containing bulky/clumsy (cloud-like) hypolobulated nuclei and definitive maturation defects
C	Clinical stages	MF	Staging of myelofibrosis
C1	Early clinical stages
	Normal hemoglobin or slight anemia, grade I: hemoglobin > 12 g/dL	MF 0	Prefibrotic stage PMGM/PMF	RF 0/1
	No, slight or moderate splenomegaly on ultrasound scan or CT	MF 1	Early fibrotic PMGM/PMF	RF 2
	Hypercellular ET, platelets in excess of 400, 600 or even > 1000 × 109/L
	No leuko-erythroblastic blood picture and/or tear drop erythrocytes
C2	Intermediate clinical stage
	Anemia grade II: hemoglobin > 10 g/dL	MF 2	Manifest fibrotic PMGM/PMF	RF 3 = RCF
	Definitive leuko-erythroblastic blood picture and/or tear drop erythrocytes	MF 3	Advanced fibrotic PMGM/PMF	RF 4 = RCF
	Splenomegaly, increased LDH
C3	Advanced clinical stage
	Anemia grade III: hemoglobin < 10 g/L	MF 3	Osteosclerosis
	Splenomegaly and increased, normal or decreased platelet count
	Thrombocytopenia, leukocytosis,leukopenia, increased circulating CD34+ cells

ET: Essential thrombocythemia; PMGM: Primary megakaryocytic and granulocytic myeloproliferation; CT: Computed tomography; LDH: Lactodehydrogenase; PV: Polycythemia vera; CML: Chronic myeloid leukemia; PMF: Primary myelofibrosis; MF: Myelofibrosis; RF: Reticulin fibrosis; RCF: Reticulin/collagen fibrosis.