Chronic myeloproliferative disorders (CMPD) include CML, polycythemia vera (PCV), myelofibrosis with myeloid metaplasia (MMM), and essential thrombocythemia (ET). Each is a clonal proliferation of a pluripotent stem cell that can differentiate along granulocytic, erythroid, and megakaryocytic lines. Each has a chronic course that often terminates as acute leukemia or myelofibrosis. CMPD are more common in adults.

PCV is characterized by excessive proliferation of all three cell lines resulting in high red cell mass, leukocytosis, and thrombocytosis.

MMM is characterized by some degree of fibrosis of the marrow, extramedullary hematopoiesis causing massive splenomegaly, and circulating normoblasts, immature granulocytes, and abnormal platelets.

ET is characterized by very high and persistent thrombocytosis, including presence of abnormal platelets. Bleeding problems or coagulopathy occur.

CMPD Abnormalities

+1q	PCV, MMM
-7	MMM
+8	PCV, MMM
+9	PCV,MMM
del(13q) interstital or terminal	PCV,MMM
del(20)(q11.2) or (q11.2q13.1)	PCV,MMM
t(9;22)(q34;q11.2)	ET

University of Wisconsin Cytogenetic Services