Altered neutrophil maturation patterns that limit identification of myelodysplastic syndromes

Background: Altered neutrophil maturation patterns have been reported useful for identification of myelodysplastic syndromes (MDS). Methods: Neutrophil maturation patterns based on CD11b, CD13, and CD16 were visually and numerically evaluated in 19 control, 23 MDS, 37 nondiagnostic for MDS (NDM) specimens, and 19 also processed 1 and 2 days subsequently. Results: In contrast to maturation patterns illustrated previously by others as "normal," 84% of controls displayed diminished acquisition of CD16, imparting a contracted appearance. Such divergence from published "normal" patterns was usually mild-moderate, considered nonspecific, and associated with delayed processing: longer intervals between collection and processing (median 20.5 vs. 5.2 h), and following 1 and 2 days delay. Findings restricted to nonspecific contraction were found in 56% MDS and 78% NDM specimens. Evaluation for aberrant patterns was still performed with mild-moderate contraction present, but concern for over interpretation led to use of an equivocal-aberrant category. Nine cases had aberrant or equivocal-aberrant patterns (seven MDS, two NDM) with distinct visual alterations that differed from nonspecific contraction and had numerical evidence for a left shift: myeloblasts increased (67%) and least mature neutrophils (CD11b-/low, CD16-/low) increased (78%). Although evidence for a left shift was associated with MDS, it was also seen in NDM specimens with a synchronous left shift. Conclusions: Neutrophil maturation patterns that diverge from previously illustrated "normal" patterns, not specific for MDS, may be common in some settings. Laboratories seeking to implement FC evaluation for MDS must determine which findings have sufficient specificity for MDS within their own practice and patient population.