[XE-2100: platelet clumps or polymorphonuclear neutrophil aggregates, that is the question].

Leukoagglutination of polymorphonuclear neutrophils is described as a rare phenomenon but its incidence is certainly underestimated. We report here 4 cases showing why this phenomenon is sometimes difficult to detect. In each case, the only flag reported from the hematology analyser XE-2100 (Sysmex corporation) was 'Platelet clumps?'. The graphic patterns were not suggestive of leukoagglutination but rather evoked platelet clumps. The 4 white blood cell differential scattergrams were absolutely normal and the 4 cases were not associated with leukoneutropenia. Two patients had clumps located only at the edges of the smears, and automated imaging processes, scanning only the center of the smears, may also contribute to the failure of recognising this phenomenon.