Macropolycytes: Severe stress time for neutrophils.

Macropolycytes are giant neutrophils found in a variety of benign and neoplastic conditions. Since megaloblastic anaemia is one of the recognised causes of macropolycytes, other blood film features of megaloblastic anaemia should be sought when they harbor hypersegmented nuclei. When they are hypolobulated and hypogranular, the occurrence of a myelodysplastic syndrome must be investigated. Finding macropolycytes in the context of a nonspecific reactive granulopoiesis is more questionable but is often associated with stressed myelopoiesis and/or granulocyte colony-stimulating factor therapy.