WHO 2016 diagnostic criteria for polycythemia vera (PV)

WHO Diagnostic Criteria for Polycythemia Vera

Diagnoses polycythemia vera according to WHO criteria. Result displays either meets criteria or does not meet criteria.

Major Criteria

Major Criterion 1: Elevated hemoglobin / hematocrit or increased red cell mass: hemoglobin > 16.5 g/dL in men or > 16.0 g/dL in women, or hematocrit > 49% in men or > 48% in women, or increased red cell mass Major Criterion 2: Bone marrow biopsy showing hypercellularity for age with panmyelosis (trilineage growth including erythroid, granulocytic, and megakaryocytic proliferation) Major Criterion 3: Presence of JAK2 V617F or JAK2 exon 12 mutation

Minor Criterion

Minor Criterion: Subnormal serum erythropoietin level

Optional WHO Exception

Apply the WHO exception for sustained absolute erythrocytosis, where bone marrow biopsy may be omitted if Major Criterion 1 is met at a very high level, JAK2 mutation is present, and EPO is low

Use this only when sustained absolute erythrocytosis is established: hemoglobin > 18.5 g/dL in men or > 16.5 g/dL in women, or hematocrit about 55.5% in men or 49.5% in women.

Major met: 0 / 3

Minor met: 0 / 1

Result will appear here

WHO rule used: diagnosis of polycythemia vera requires all 3 major criteria or the first 2 major criteria plus the minor criterion. Optional exception included for sustained absolute erythrocytosis cases described in the WHO criteria.

WHO 2016 Diagnostic Criteria for Polycythemia Vera

The WHO 2016 diagnostic criteria for polycythemia vera (PV) are used to distinguish PV, a clonal myeloproliferative neoplasm, from secondary causes of erythrocytosis. The 2016 revision emphasized earlier and more accurate detection, especially of so-called “masked” PV, by lowering hemoglobin thresholds and making bone marrow morphology a major diagnostic criterion.

The criteria

Diagnosis of PV requires either all 3 major criteria or the first 2 major criteria plus the minor criterion.

Major criterion 1: Evidence of increased red cell mass, defined by any of the following:

Hemoglobin > 16.5 g/dL in men or > 16.0 g/dL in women, or
Hematocrit > 49% in men or > 48% in women, or
Increased red cell mass.

Major criterion 2: Bone marrow biopsy showing hypercellularity for age with panmyelosis, meaning trilineage proliferation involving erythroid, granulocytic, and megakaryocytic lineages. The megakaryocytes are typically pleomorphic and mature.

Major criterion 3: Presence of a JAK2 V617F mutation or JAK2 exon 12 mutation. JAK2 mutations are present in nearly all patients with PV and are a central part of confirming clonality.

Minor criterion: Subnormal serum erythropoietin (EPO) level. A low EPO level supports autonomous erythrocytosis and helps distinguish PV from secondary erythrocytosis.

Why the 2016 revision mattered

Compared with older criteria, the 2016 WHO revision lowered the hemoglobin thresholds and gave bone marrow biopsy a more prominent role. This change was intended to improve recognition of patients with masked PV, who may not have strikingly high hemoglobin values but still have true PV and its associated thrombotic risk.

Bone marrow biopsy exception

The WHO criteria also describe a limited exception in which bone marrow biopsy may be omitted for diagnostic purposes in patients with sustained absolute erythrocytosis, a JAK2 mutation, and subnormal EPO. The cited thresholds for this exception are hemoglobin above 18.5 g/dL in men or 16.5 g/dL in women, or hematocrit above about 55.5% in men or 49.5% in women. Even so, many experts still favor marrow examination because it can establish a baseline and provide prognostic information.

How the criteria are used in practice

In practice, evaluation usually includes a CBC, review of hemoglobin and hematocrit, JAK2 mutation testing, serum EPO measurement, and often bone marrow biopsy. The criteria are applied alongside clinical judgment to distinguish PV from secondary erythrocytosis caused by hypoxia, smoking, testosterone use, renal disease, or EPO-producing tumors.

Strengths and limitations

The 2016 WHO criteria improved sensitivity for diagnosing PV, but they also increased reliance on marrow interpretation and molecular testing. In borderline cases, diagnosis can still be challenging, especially when there is iron deficiency, plasma volume contraction, or overlap with other myeloproliferative neoplasms. This is why the criteria are best used as part of a full hematologic assessment rather than in isolation.

Summary

The WHO 2016 PV criteria diagnose polycythemia vera when a patient has:

all 3 major criteria, or
major criteria 1 and 2 plus the minor criterion.

They were designed to catch PV earlier, especially masked disease, by using lower hemoglobin/hematocrit thresholds and incorporating marrow morphology into the core definition.