Page 227 - Essential Haematology

Chapter 15 Myeloproliferative neoplasms / 213

the increase in blood viscosity leads to ■ The predominant feature of primary
headaches, plethoric appearance and myelofi brosis is a progressive generalized
splenomegaly. reactive fi brosis of the bone marrow in
■ Treatment aims to maintain the association with the development of

haematocrit around 0.45. Useful haemopoiesis in the spleen and liver.
approaches include venesection or Symptoms usually result from anaemia and
hydroxyurea and aspirin is also given. a grossly enlarged spleen.
JAK2 inhibitors are being assessed in ■ Diagnosis is made on blood fi lm, which

clinical trials. Survival is usually over 10 shows a leucoerythroblastic appearance,
years but there may be progression to together with bone marrow biopsy and
leukaemia or myelofi brosis. JAK2 mutation screen. Treatment is with

■ Secondary polycythaemia can arise from red cell transfusion. Splenectomy is
rare congenital causes or acquired sometimes used and JAK2 inhibitors
disorders such as lung disease or tumours appear encouraging.

that secrete erythropoietin. Venesection ■ Systemic mastocytosis is a clonal

may be needed. proliferation of mast cells with involvement

■ Essential thrombocythaemia is diagnosed of bone marrow, skin (as uticaria
by persistent raised platelet count in the pigmentosa) and other organs.
absence of other causes. JAK2 is mutated
in approximately 50% of cases.

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