The myeloproliferative neoplasms (MPN) are clonal myeloid disorders characterized by proliferation of mature myeloid cells, such that in polycythaemia vera (PV), the red cell proliferation dominates, platelets in essential thrombocythaemia (ET) and in myelofibrosis (MF), there may be cytopenia or proliferation, but the characteristic feature is the strikingly abnormal bone marrow stroma. These ...