Neutrophils that are significantly larger than normal, their nuclei may appear hypersegmented at first sight but in fact consist of two distinct nuclei that have normal lobation. Sometimes the nuclei overlap, in other cases they may almost appear as mirror images.
Images of macropolycytes
The first example (image 1) shows a macropolycyte (lower cell) compared with a normal band neutrophil. The cells each have an activated appearance but note the difference in size and nuclear form. The second (also activated) shows the two distinct nuclei very clearly (image 2). Finally, a partially degranulated eosinophil macropolycyte with two tri-lobed nuclei from a hypereosinophilic syndrome (image 3).
Macropolycytes are tetraploid neutrophils with two separate nuclei within a single cell (i.e. they are produced by nuclear division without cytoplasmic division), often occurring during accelerated myelopoiesis. They have been reported in adults with B12 or folate deficiency, myeloid leukaemias, sepsis, or following cytotoxic chemotherapy.
It is easy to initially confuse these appearances with neutrophil hypersegmentation, it is important to recognise the significantly increased size of macropolycytes, and the two separate nuclei.