The myelodysplastic syndromes (MDSs) are characterized by ineffective hematopoiesis, often accompanied by dysplastic changes in the maturing cells. PMNs may show hyposegmentation as a bilobed pseudo-Pelger-Huet cell (as shown) or a unilobate mature cell. The true Pelger-Huet anomaly is a harmless inherited variant. PMNs in MDSs may also show hypersegmentation (5 or more lobes) and must then be distinguished from B12 and folate defiency.
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