Polycythemia Vera


Slides of Polycythemia Vera: Polycythemia vera is a clonal stem cell disorder characterized by excessive erythrocyte production. Its etiology is not fully established, but hypersensitivity to interleukin-3 may play a role in the sustained erythrocytosis observed in this disease.

Polycythemia vera usually occurs within the age range of 20-80, with 60 being the mean age of onset. The disease is slightly more common in males than in females. Clinical features include headaches, weakness, weight loss, and pruritus (itching without visible eruption on the skin). 10-15 % of patients may also present with gout due to hyperuricemia. Hemorrhage, thrombosis and hyperviscosity may be evident at any time. Splenomegaly, as a result of vascular congestion, is seen in 75% of patients at the time of presentation. Hepatomegaly is observed in about 30% of cases.

A diagnosis of polycythemia vera is made when a patent fulfills all three of the major criteria, or any two major and any two minor criteria.

  • Major Criteria
    • total RBC vol men > 36 mg/kg; women >32 mg/kg
    • arterial 02 saturation > 92%
    • Splenomegaly
  • Minor Criteria
    • Platelet count > 400 x 10^9/L
    • Leukocytosis > 12 x 10^9/L
    • LAP > 100 (no infection)
    • Serum B12 > 900 pg/ml or UB12 BC> 2200 pg/ml

    Polycythemia vera is considered one of the chronic myeloproliferative disorders. Other diseases in this category include: agnogenic myeloid metaplasia, essential thrombocythemia, and chronic myelogenous leukemia.

    Peripheral blood findings for polycythemia vera include:

    • Increased hemoglobin & hematocrit
    • Normal red blood cell morphology, unless iron deficient or spent phase
    • Normoblasts may be present
    • Mild to moderate leukocytosis
    • Mild neutrophilia and/or basophilia
    • Thrombocytosis

    Bone marrow findings for Polycythemia vera include

    • Moderate to marked hypercellularity
    • trilineage hyperplasia
    • megakaryocytes increased; hyperlobulated
    • dilated sinusoids with intravascular hematopoiesis
    • decreased or absent iron stores
    • increased reticulin (only in a minority of patients)

 


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