What is post-polycythemic myeloid metaplasia?
Post-polycythemic myeloid metaplasia (PPMM) is also referred to as the “spent phase”. After years of hyperactivity, the marrow may become increasingly fibrotic or scarred (myelofibrosis), hematopoiesis (blood production) becomes ineffective and peripheral blood counts decrease, and the spleen usually becomes enlarged. The marrow becomes hypo cellular (fewer blood-forming cells) as opposed to the hypercellular (many blood-forming cells) state in the proliferative phase. During this phase, hematopoiesis may resemble that seen in aplastic anemia, sideroblastic anemia, refractory anemia, or paroxysmal nocturnal hemoglobinuria. As the condition worsens, constitutional symptoms such as fatigue, loss of appetite, weight loss, and night sweats may increase. Some patients seem to have growth factors (at a cellular level) that predispose them to the development of fibrosis. Interferon has retarded or reversed this in some patients but is not effective in all.
Post polycythemic myeloid metaplasia (PPMM) is also referred to as the “spent phase”. After years of hyperactivity, the marrow may become increasingly fibrotic (scarred), hematopoiesis (blood production) becomes ineffective and peripheral blood counts decrease. The marrow becomes hypocellular as opposed to the hypercellular state in the proliferative phase. During this phase, hematopoiesis may resemble that seen in aplastic anemia, sideroblastic anemia, refractory anemia, or paroxysmal nocturnal hemoglobinuria. Some patients seem to have growth factors that predispose them to the development of fibrosis. Interferon has retarded or reversed this is some patients but is not effective in all. Bone marrow transplantation is being used at some centers to treat myelofibrosis.
