Biology and management of idiopathic myelofibrosis.

Idiopathic myelofibrosis (IMF) is a hematopoietic stem cell disorder characterized by hypercellularity of the bone marrow with an increase in abnormal megakaryocytes, varying degrees of marrow fibrosis, and extramedullary hematopoiesis. The central lesion of the IMF stem cell is not known; however, the marrow fibrosis is a polyclonal reaction to inflammatory mediators generated by the transformed clone. Historical management approaches have centered on improving the patient's blood counts in a palliative manner. Recent reports of autologous and allogeneic bone marrow transplantation (BMT) in IMF patients indicate that stable engraftment occurs easily, the marrow fibrosis is a reversible process, and a graft-versus-fibrosis effect may exist. The goals of future therapies will target marrow fibrosis and harness the graft-versus-fibrosis effect to safely and effectively treat patients with IMF.