Myelofibrosis: biology and treatment options.

Primary myelofibrosis (PMF), also known as idiopathic myelofibrosis or myelofibrosis with myeloid metaplasia, a chronic myeloproliferative disorder, is a rare disease mainly affecting older people, with a median survival of 3.5–5 yr (1), characterized by bone marrow fibrosis, extramedullary haemopoiesis, and the presence of tear drop red cells in the peripheral blood (2). Clinical manifestations of PMF include splenomegaly, progressive anaemia and constitutional symptoms. The pathogenesis of the disease is currently not understood. PMF is a clonal disorder of the haematopoietic stem cell in which the fibrosis is a reactive process involving the interaction of multiple cytokines, such as the platelet-derived growth factor (PDGF), transforming growth factor beta 1 (TGF-b1), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) (3–5) produced by the CD34+ cells, the megakaryocytes, and the monocytes.