Histologically, MDS-EB is identified by the presence of increased myeloblasts in the bone marrow, typically between 5% to 19%. The bone marrow aspirate and biopsy reveal dysplastic changes in one or more of the hematopoietic cell lines, including erythroid, granulocytic, and megakaryocytic lineages. Common findings include:
- Erythroid Dysplasia: Abnormalities in red blood cell precursors, such as nuclear budding, multinucleation, and megaloblastoid changes. - Granulocytic Dysplasia: Neutrophils showing hypogranulation, nuclear hypolobation, or pseudo-Pelger-Huët anomaly. - Megakaryocytic Dysplasia: Micromegakaryocytes, megakaryocytes with multiple separated nuclei, and other abnormal forms.
