Macropolycytes as a sepsis biomarker.

A 16-year-old male patient who underwent a kidney transplant developed a septic shock. A full blood count (FBC) was performed and the presence of monocytosis in the automatic FBC, the overlap between neutrophils and monocytes in the WBC scatter plot, and a "MO blast" flag triggered by the analyzer, led to a peripheral blood film (PBF). PBF revealed the presence of macropolycytes that were erroneously count as monocytes by the analyzer. Macropolycytes can play an important role as a sepsis biomarker.