[Idiopathic myelofibrosis. Main pathogenetic, prognostic and therapeutic aspects].

Primary myelofibrosis is a complex disorder characterized by bone marrow fibrosis with no apparent cause. It is known in literature under a wide number of terms, reflecting the variety of clinical features and the different pathogenetic hypotheses. In most cases it is plain that marrow fibrosis is secondary to a clonal myeloproliferative disorder and, in particular, to the presence of abnormal megakaryocytes secreting (MKDGF/PDGF); but probably some other growth factors synthesized by megakaryocytes and contained in platelet alpha-granules are involved. The molecular event that determines the advantage of the clonal growth is, at present, unknown, and the pathogenetic importance of some chromosome anomalies is still under discussion. Over the last years, besides megakaryocyte dysplasia, several fibrogenetic mechanisms such as a bone marrow immune damage have been taken into consideration. Studies on prognostic factors regarding the main clinical, hematological and histological parameters have given conflicting results, because of low incidence of the disease, different criteria used for the diagnosis, and different terms of the clinic presentation of the pathology. Although a great deal of progress has been made in terms of pathogenetic mechanisms, a lot of questions must be still definitively settled, further in depth studies still have to go into many matters.