Myeloproliferative disorders.

Myeloproliferative disorders result from monoclonal proliferation of the pluripotential hematic precursor cell, with preservation of its capacity to differentiate and mature into functional progeny. Phenotypic expression varies with the degree of involvement of each derivative cell type and the extent to which growth is hyperplastic, dysplastic, or malignant. Hyperplastic bone marrow with increased circulating erythrocytes and platelets, reactivation of hematopoiesis in long bones and extramedullary sites, and the development of secondary marrow fibrosis are responsible for complications of thrombosis, hemorrhage, splenic infarction, hypersplenism, and anemia. A predilection for the geriatric population, chronicity, and great variability in phenotypic expression present a challenge in diagnosis and management. Individualized treatment based on thorough understanding of the pathophysiology of myeloproliferative disease is required to maximize complication-free survival by avoiding both the risk of the disease and its therapy and utilizing all available supportive measures in the prevention and treatment of complications.