Myelodysplastic Syndromes

The myelodysplastic syndromes are characterized by maturational defects and ineffective hematopoesis. The marrow appears normal to hypercellular. By definition, the marrow is less than 30% blasts. All three lineages are affected. Symptoms include marrow failure, anemia, pedichiae, bruising. Hepatosplenomegaly is rare. RBCs may appear "megaloblastoid, similar to folate or B12 deficiency. These disorders are more common in adults, usually more than 60 years of age. Often the etiology appears to DNA damage such as exposure to alkylating agents or radiation, or the presence of a DNA repair defect. These disorders may progress to AML. Treatment is supportive with transfusions or stem cell therapy. Typical features of each cell line are:

RBCs: ringed sideroblasts (excess iron demonstrated by Prussian blue stain)
PMNs: Döhle bodies, toxic granulations, and pseudo-Pelger-Huet nuclei (bi-lobed nuclei)
Megakaryocytes: Pawn ball megakaryocytes, with multiple, separate nuclei.

The FAB Classification of myelodysplastic syndromes

RA	Refractory Anemia
RARS	Refractory Anemia with Ringed Sideroblasts
RAEB	Refractory Anemia with Excess Blasts
RAEBIT	Refractory Anemia with Excess Blasts in Transformation
CMML

Myeloid Disorders

Heme-Onc

Net Scut Home

Please direct all comments to:

Last modification: May 2, 1999