Overview of Myeloproliferative Neoplasms By Jane Liesveld, MD, James P Wilmot Cancer Institute, University of Rochester Medical Center Reviewed / Revised Jul 2022 | Modified Sep 2022 View Patient Education More Information Topic Resources Classification of Myeloproliferat... Myeloproliferative neoplasms are clonal proliferations of bone marrow stem cells, which can manifest as an increased number of platelets, red blood cells (RBCs), or white blood cells (WBCs), alone or in combination, in the circulation and sometimes with fibrosis in the bone marrow and extramedullary hematopoiesis (cell production outside the marrow).