Megaloblastoid erythroid changes

These are larger than usual erythroid (RBC) precursors with relatively immature nuclear features for the maturity of the cytoplasm (nuclear/ cytoplasmic maturation asynchrony). Causes include certain vitamin deficiencies (e.g. B12 or Folate deficiency), drug effects such as methotrexate or due to an underlying Myelodysplastic Syndrome (MDS).