Color Atlas of Hematology - Practical Microscopic and Clinical ...

106Abnormalities of the White Cell SeriesMyelodysplasia (MDS)Clinical practice has long been familiar with the scenario in which, afteryears of bone marrow insufficiency with a more or less pronounced deficitin all three cell series (tricytopenia), patients pass into a phase of insidiouslyincreasing blast counts and from there into frank leukosis—although the evolution may come to a halt at any of these stages. Thetransitions between the forms of myelodysplastic syndromes are veryfluid, and they have the following features in common:➤ Anemia, bicytopenia, or tricytopenia without known cause.➤ Dyserythropoiesis with sometimes pronounced erythrocyte anisocytosis;in the bone marrow often megaloblastoid cells and/or ring sideroblasts.➤ Dysgranulopoiesis with pseudo-Pelger-Huët nuclear anomaly (hyposegmentation)and hypogranulation (often no peroxidase reactivity) ofsegmented and band granulocytes in blood and bone marrow.➤ Dysmegakaryopoiesis with micromegakaryocytes.The FAB classification is the best-known scheme so far for organizing thedifferent forms of myelodysplasia (Table 17).Table 17Forms of myelodysplasiaForm of myelodysplasia Blood analysis Bone marrowRA = refractory anemiaRAS = refractory anemiawith ring sideroblasts( aquiredidiopathic sideroblasticanemia, p. 137)RAEB = refractory anemiawith excess ofblastsAnemia (normochromicor hyperchromic);possiblypseudo-Pelger granulocytes;blasts 1%Hypochromic andhyperchromic erythrocytesside by side,sometimes discretethrombopenia andleukopenia; pseudo-Pelger cellsOften thrombocytopeniain addition toanemia; blasts 5%,monocytes 1000/µl,pseudo-Pelger syndromeDyserythropoiesis(marginal dysgranulopoiesisand dysmegakaryopoiesis 10%) 5% blastsMore than 15% of thered cell precursors arering sideroblasts;blasts 5%Erythropoietic hyperplasia(with or withoutring sideroblasts);5–20% blastsCont. p. 108