Miscellaneous.

Polycythemia vera (Vaquez-Osler disease) — PCV — was first described in the year 1892 by Vaquez. Today the understanding is that PCV is a clonal neoplastic disease with the proliferation of erythrocytes. Together with chronic myelocytic leukemia, osteomyelofibrosis (OMF) and thrombocythemia, it is included in the group of myeloproliferative diseases (MPD). All the bone marrow elements (erythrocytes, megacaryocytes, granulocytes, and fibroblasts) are involved in the hyperplasia but erythropoiesis is the dominant factor. Also extramedullary hematopoiesis is possible. Hypervolemia, increased cardiac output, hyperviscosity and the resultant impaired blood flow are the reasons for most clinical manifestations. [ABSTRACT FROM AUTHOR]