Myeloid metaplasia with myelofibrosis

• Proliferation of neoplastic myeloid stem cells mostly in the spleen (myeloid metaplasia)

• Without a pre-existing syndrome (such as p. vera or CML) this is called agnogenic (idiopathic) myeloid metaplasia

• Mostly in people > 50 YOA who c/s of splenomegaly and progressive anemia

• Peripheral smear shows tear-shaped erythrocytes (dacrocytes), leukoerythroblastosis (from extramedullary hematopoiesis and fibrosis pushing out precursors), and abnormal (“giant”) platelets

• Marrow typically hypocellular with atypical appearing megakaryocytes and a variable degree of fibrosis (fibroplastic proliferation from elaboration of growth factors by neoplastic megakaryocytes)

• Myelofibrotic pattern may be seen in the “burnt out” phases of CML and p. vera

• Course is highly variable and people often die from infection, thrombosis, bleeding, or transformation into leukemia (5-20% of cases)

• Median survival from 1-5 years

Category: Medical Subject Notes , Pathology Notes