Medline ® Abstract for Reference 137

Dysmegakaryocytopoiesis is an integral component of myelodysplastic syndrome (MDS), and has been shown in some studies to be an independent prognostic factor. Megakaryocytic hypogranulation, a feature we have noticed for some time to be fairly common in MDS and acute myeloid leukaemia (AML), has received little attention in the literature as a dysplastic feature of megakaryocytes. This study was performed to determine how frequently this feature was observed in MDS and the specificity of its occurrence. On review of archival materials, hypogranular megakaryocytes were observed in 80.3% of MDS, 30.6% of AML and 1.4% of controls. On the other hand, the other well-recognized dysmegakaryocytopoietic features (hypolobulation, multiple separate nuclei, micromegakaryocyte), though frequent in MDS or AML, were also observed in 20% of controls. We therefore propose including megakaryocytic hypogranulation as a cytological feature of myelodysplasia.