Myelodysplastic syndromes

on 7.2.09 with 0 comments

  • Myelodysplastic syndromes are stem cell d/o characterized by maturational defects resulting in ineffective hematopoiesis and risk of transformation into AML (called “preleukemia” syndromes)

  • Clinical features

    • There may be cytopenias and dysmorphic changes in the peripheral smear with normal or hypercellular marrow

    • If there is anemia it’s usually macrocytic and there may be monocytosis

    • Most often in males 60-70 YOA

    • May be asymptomatic or present with weakness, hemorrhage, and/or infection

    • Chromosomal abnormalities are in up to 2/3 of patients and indicate a poor prognosis and increased risk of progressing to AML

    • Median survival depends on form of myelodysplasia and presence of karyotypic abnormalities

  • Peripheral smear changes affect all 3 lineages (erythroid, myeloid, and megakaryocytic)

    • Erythroid

      • Ringed sideroblasts (erythroblasts with iron-laden mitochondria that can be seen as perinuclear granules with a Prussian-blue stain

      • Megaloblastoid maturation like that seen with B12 or folate deficiency

      • Nuclear budding abnormalities (nuclei with misshapen, often polypoid outlines)

    • Myeloid

      • Neutrophils may contain decreased number of secondary granules or contain toxic granulations and Dohle bodies

      • Pseudo-Pelger-Huet cells (neutrophils with a nucleus with only 2 lobes) are often seen

      • Neutrophils may appear to completely lack nuclear segmentation

      • Myeloblasts may be increased but are <>

    • Megakaryocytes – may have single nuclear lobes or multiple nuclei (pawn ball megakaryocytes) instead of a single multilobed nucleus

  • Classification

    • RA (refractory anemia)

      • <>

      • Good prognosis

    • RARS (refractory anemia with ringed sideroblasts)

      • Differs from RA only in that there are more ringed sideroblasts (> 15%)

      • Good prognosis

    • RAEB (refractory anemia with excess blasts)

      • <5%>

      • Median survival only 11 months (tends to progress to leukemia)

    • RAEB-T (refractory anemia with excess blasts in transformation)

      • Lots (21-29%) of blasts in marrow and blood

      • Very poor prognosis

    • CMML (chronic myelomonocytic leukemia)

      • <>

      • Same prognosis as RAEB not because of transformation to leukemia but because these people tend to die of infection

      • See monocytosis (this is how you tell this apart from CML; CML has basophila, CMML has monocytosis)

    • CMML-T (chronic myelomonocytic leukemia in transformation)

      • 21-29% blasts in marrow and blood

      • Will see monocytosis

      • Generally, the more blasts the worse the prognosis (more likely to go onto leukemia)

  • Other processes that cause dysmyelopoietic maturation

    • Megaloblastic anemia of B12/folate deficiency

    • Chemotherapeutic drugs

    • Alcohol

    • Heavy metal intoxication

    • AIDS and autoimmune d/o

    • Paroxysmal nocturnal hemoglobinuria

Category: Medical Subject Notes , Pathology Notes



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