Myeloproliferative disorders Flashcards
What are myeloproliferative disorders?
Disorders caused by clonal proliferation of haematopoietic myeloid stem cells in the bone marrow
These cells retain the ability to differentiate into RBCs, WBCs, plts, causing an excess of one or more of these.
Name the myeloproliferative disorder caused by proliferating RBCs
Polycythaemia vera (PRV)
Name the myeloproliferative disorder caused by proliferating WBCs
Chronic myeloid leukaemia (CML)
Name the myeloproliferative disorder caused by proliferating platelets
Essential thrombocythemia
Name the myeloproliferative disorder caused by proliferating fibroblasts
Myelofibrosis
Name the two types of polycythaemia
Relative
Absolute
Describe relative polycythaemia
Decreased plasma volume, normal red cell mass
What causes acute relative polycythaemia
Dehydration
What causes chronic relative polycythaemia
Obesity
HTN
High alcohol and tobacco intake
What is absolute polycythaemia
Increased RBC mass
How is absolute polycythaemia classically measured
By dilution of autologous radioactive chromium labelled RBCs
What causes primary absolute polycythaemia
Polycythaemia vera
What causes secondary absolute polycythaemia
Hypoxia - high altitudes, CLD, CCHD, heavy smoking
Increased EPO production - renal and hepatocellular carcinoma
What is polycythaemia vera?
The malignant proliferation of a clone derived from one pluripotent stem cell.
The erythroid progenitor offspring as unusual in not needing erythropoietin to avoid apoptosis
Excess proliferation of RBC, WCC, plts leading to hyper viscosity and thrombosis
What mutation is associated with polycythaemia vera?
JAK2 (JAK 2 V617F)
What age is polycythaemia vera commoner in?
> 60
How may someone with polycythaemia vera present
Asymptomatic - abnormal FBC
Vague symptoms of hyper viscosity - headaches, dizziness, tinnitus, visual disturbance, itching after a hot bath and erythromelalgia, burning sensation in fingers and toes
What signs may someone with polycythaemia vera have?
Facial plethora
Splenomegaly
Gout - increased urate from RBC turnover
Features of arterial or venous thrombosis
What investigations would you do when suspecting polycythaemia vera?
FBC - Increased RBC, Hb, HCT, PCV, WCC, Plts
Increased B12
Marrow - hypercellularity with erythroid hyperplasia
Cytogenetics - required to differentiate from CML
Decreased serum EPO
Raised red cell mass on chromium studies and splenomegaly in the setting of normal PaO2 is diagnostic
Describe how you would treat polycythaemia vera
Aim to keep HCT <0.45 to decrease risk of thrombosis - venesection if low risk, hydroxycarbamide or alpha-interferon (if pregnant) if high risk
Aspirin 75mg daily
Describe the prognosis of polycythaemia vera
Variable, many remain well for many years
Thrombosis and haemorrhage are the main complication
Transition to myelofibrosis occurs in 30% and acute leuakaemia in 5%
What monitoring is required in polycythaemia vera?
FBC every 3 months
What is essential thrombocythemia
A clonal proliferation of megakaryocytes leading to persistently high platelets often >1000X10^9/L with abnormal function, causing bleeding or arterial/venous thrombosis and microvascular occlusion - headache, abnormal chest pain, light-headedness and erythromelalgia
How is essential thrombocythemia treated
Exclude other causes of thrombocytosis
Aspirin 75mg OD
Hydroxycarbamide for high risk patients
