0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:17
Myelodysplastic Syndrome 1029■Dyserythropoiesis: multinuclear forms, nuclear fragments, mega-
loblastic changes, nuclear:cytoplasmic dyssynchrony, ringed sider-
oblasts on iron stain
■Dysthrombopoiesis: bizarre nuclear forms, decreased ploidy, “pawn
ball” nuclei, micromegakaryocytes
■Increased myeloblastsOther Tests:
■Cytogenetics on bone marrow; characteristic abnormalities=dele-
tions (e.g., 5q-, 7q-, 20q); numerical abnormalities (monosomy 7,
trisomy 8); translocations (e.g., t(3;21), t(5;12), t(1 1;16))
■Classification: undergoing revision. Current FAB nomenclature
(French-American-British) categories: refractory anemia (RA, <5%
marrow blasts); refractory anemia with ringed sideroblasts (RARS,
<5% marrow blasts, >15% ringed sideroblasts); refractory anemia
with excess blasts (RAEB, 5–20% marrow blasts); refractory ane-
mia with excess blasts in transformation (RAEB-T, 20–30% marrow
blasts). AML≥30% marrow blasts.
■Chronic myelomonocytic leukemia (CMML) requires >1,000 mon-
cytes/mI. Newer classification schemes: >20% marrow blasts=
AML.
differential diagnosis
■Congenital Disorders
■Hereditary sideroblastic anemia (usually microcytic rather than
macrocytic)
➣Fanconi’s anemia (short stature, radial abnormalities)
➣Diamond-Blackfan syndrome
➣Kostmann’s syndrome
➣Shwachman’s syndrome
➣Down syndrome
■Vitamin Deficiency
➣B12, folate or iron deficiency
■Drug toxicity
■Marrow suppression from oral or parenteral medications
➣Toxins
➣Chemotherapy and/or radiation therapy
➣Alcohol
■Anemia of Chronic Disease
■Renal failure
➣Chronic infection, including tuberculosis
➣Rheumatologic and autoimmune disorders