ABSTRACT
Primary myelofibrosis (PMF) is an uncommon clonal stem cell disorder characterized by the autonomous proliferation of myeloid and granulocytic elements with panmyelosis, marked and diffuses bone marrow (BM) fibrosis, leukoerythroblastic blood picture with teardrop poikilocytosis and extramedullary hematopoiesis with progressive hepatosplenomegaly. Patients with PMF are usually diagnosed late in life and usually present with symptoms of BM failure such as fatigue and dyspnea, bleeding, night sweats, and fever. The prefibrotic stage of PMF is characterized by hyper-cellular marrow with increased myeloid-to-erythroid ratio and megakaryocytic hyperplasia with prominent atypia. Megakaryocytes display a morphologic feature similar to those observed in the fibrotic stage. Prefibrotic phase of PMF differs from essential thrombocythemia by displaying more prominent megakaryocytic atypia with abnormal maturation, hyperchromasia and irregularly folded nuclei and presence of large clusters of megakaryocytes. Most PMF patients will progress and finally die from the cause related to the disease, including BM failure, thromboembolic events, portal hypertension, cardiac failure, and leukemic progression.
