Polycythemia Emmanuel Akuna 1412

Lab values. Normal platelet 150, ,000 CELLS/MM 3 Hemoglobin- men g/dl women g/dl Hematocrit (HCT) Men % women % Red cell count ×10 6 /mm 3 Men Women Normal Total WBC count == 4500 – /cubic millimetre

Polycythemia, or erythrocytosis denotes an increase in red cells per unit volume of peripheral blood usually in association with an increase in hemoglobin concentration

Polycythemia may be: absolute (defined as an increase in total red cell mass) relative.

Absolute polycythemia described as: Primary: when the increased red cell mass results from an autono-mous proliferation of erythroid progenitors (polycythemia vera) Secondary: when the excessive proliferation stems from elevated levels of erythropoietin.

Polycythemia Vera (primary) Neoplastic proliferation of mature myeloid cells, especially RBC. Granulocyte and platelets are also increased. Associated with JAK2 mutation, A tyrosine kinase Valine to phenylalanine substitution at residue 617 Decreased EPO.

Morphology The major anatomic changes in polycythemia vera stem from increases in blood volume and viscosity liver is enlarged spleen usually is slightly enlarged (250 to 300 g) thromboses and infarctions( Due to increased viscosity and stasis)

Morphology Hemorrhages due to excessive distention of blood vessels and abnormal platelet function. (gastrointestinal tract, oropharynx, or brain are most affected.) Dysfunctional platlets Peripheral blood often shows basophilia. bone marrow is hypercellular In a subset of patients, this progresses to a spent phase where the marrow is largely replaced by fibroblasts and collagen.

Clinical symptoms Blurry vision, headache, dizziness, hematemesis, Increased risk of venous thrombosis that may give rise to Budd-Chiari syndrome Flushed face due to congestion Pruritus and gastric ulcer. Gout (5%-10%) or Asymptomatic hyperuricemia

Diagnosis Made in the lab RBC counts range from 6 to 10 million/µl hematocrit is often 60% or greater granulocyte count can be as high as 50,000 cells/L platelet count is often over 400,000/L (functionally abnormal) Basophilia is common

Treatment Phlebotomy. In those receiving no treatment, death occurs from vascular complications within months. With treatment median survival is increased to about 10 years by lowering the red cell count.

Secondary Polycythemia Increased erythropoietin levels Adaptive: lung disease, high-altitude living, cyanotic heart disease Paraneoplastic: erythropoietin-secreting tumors (e.g., renal cell carcinoma, cerebellar hemangioblastoma, hepatocellular carcinoma)

Relative polycythemia (hemoconcentration) Results from dehydration, such as occurs with water deprivation prolonged vomiting Diarrhea excessive use of diuretics

USLME CONCEPT In PV SaO2 is normal and EPO is decreased. Secoundary polycythemia due to lung disease SaO2is decreased and EPO is increased. In secoundary polycythemia due to ectopic EPO. Sao2 is normal and EPO is increased.

QUESTION?

References Robbins review of pathology Pathoma video First aid (highest yield)

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