Polycythaemia vera, essential thrombocythaemia, myelofibrosis and CML
Expansion
| Disorder | Dominant lineage | Molecular marker |
|---|---|---|
| Polycythaemia vera | Red cells | JAK2 in over 95 per cent |
| Essential thrombocythaemia | Platelets | JAK2, CALR or MPL |
| Primary myelofibrosis | Fibroblast reaction | JAK2, CALR or MPL |
| Chronic myeloid leukaemia | Granulocytes | BCR-ABL, Philadelphia chromosome |
Polycythaemia vera: raised haematocrit with low erythropoietin, distinguishing it from secondary polycythaemia where erythropoietin is high. Features include aquagenic pruritus (itch after a hot bath), erythromelalgia, splenomegaly, and a high risk of both thrombosis and haemorrhage. Treated with venesection and aspirin, with hydroxycarbamide if high risk.
Myelofibrosis: marrow replaced by fibrous tissue, so haematopoiesis moves to liver and spleen, giving massive splenomegaly and a leucoerythroblastic film with teardrop poikilocytes. Marrow aspiration gives a dry tap.
All can transform into acute leukaemia or into myelofibrosis, and all share a thrombotic tendency, which is the main cause of morbidity.