Myeloproliferative Disorders

Abstract

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.

Splenomegaly, hypersplenism, and hereditary disorders with splenomegaly

“…On the other hand, infarction is a more common complication in splenomegalic patients with hematological malignancies (e.g. agnogenic myeloid metaplasia-myelofibrosis) or collagen vascular diseases (systemic lupus erythematosis, Wegener's granulomatosis or rheumatoid arthritis with Felty's syndrome) largely attributable to the frequency of coexistent hyperproliferation and/or hypercoagulability [14][15][16].…”

Isolated Pancreatic Extramedullary Hematopoiesis

“…Extramedullary hematopoiesis (EMH) in association with myelofibrosis [1, 2], myeloproliferative disorders [3], pernicious anemia [4], thalassemia [5, 6], hereditary spherocytosis [7], myeloid leukemias [8] and ‘gray platelet’ syndrome [9] has been described commonly in the spleen and less commonly in other sites like lungs and pleura [10, 11, 12, 13], liver [14], mediastinum [7], spinal cord and paravertebral areas [5, 15], peritoneum, endometrium [16], and skin [17]. We report the first known case of isolated pancreatic EMH in the absence of splenomegaly in a patient with an ‘atypical’ myeloproliferative disorder who presented with peripheral blood leukocytosis and thrombocytosis.…”

Long term treatment of myeloproliferative disease with interferon-?-2b

“…Chronic myeloproliferative disorders (MPDs) result from monoclonal expansion of abnormal pluripotent stem cells and are characterized by abnormalities in hematopoietic cellular proliferation, quantitative and qualitative alterations in bone marrow and peripheral blood cells, and fibrosis and extramedullary expansion of the blood‐forming organ 1‐10. The latter sequela is manifested by hepatosplenomegaly, which may be debilitating even before cytopenias, varices, gastrointestinal bleeding, or ascites occur.…”

“…Conventional treatment for MPD has been comprised either of mechanical removal of increased hematopoietic populations by phlebotomy, apheresis, and splenectomy or of myelosuppression by external beam radiation, radioactive phosphorus, alkylating agents, and/or hydroxyurea 1‐3. However, these approaches are only palliative, and the disease progresses inexorably, with debilitating abdominal organomegaly, transfusion dependency, bleeding, infection, and transformation into acute leukemia.…”