Representative morphology in aspirate smear and flow cytometric gating strategy. (A) Wright-Giemsa–stained BM aspirate smear from a patient with VEXAS syndrome, demonstrating cytoplasmic vacuoles in myeloid and erythroid precursors. (B-D). Flow cytometric gating strategy for (B) neutrophil, (C) monocyte, and (D) erythroid precursors. (B) Dot plots of neutrophils selected based on their CD45 expression and SSC properties (green). The CD11b and CD13 expression on neutrophils allows for the delineation of neutrophil maturation stages, ranging from the least mature (high CD13/low CD11b) (magenta) to the most mature ones (high CD13/high CD11b) (orange).⁸ (C) The identification of monocytes (light blue) based on their intense CD64 expression and SSC properties, and the selection of immature monocytes based on their poor expression of CD14 (dark green). (D) The selection of nucleated red blood cells (brown) based on their intense CD71 expression and poor or no expression of CD45. Early red cell precursors are identified by their high CD105 and relatively low glycophorin A expression (red). The histograms on the right graphs depict the SSC intensity of precursors (neutrophil precursors, magenta; monocyte precursors, dark green; and early red cell precursors, red). Lymphocytes are selected based on CD45 and SSC properties (dark blue) and the SSC intensity of CD4⁺ cells (identified based on their coexpression of CD3 and CD4; not shown) serves as internal controls (blue lines). APC-Cy, allophycocyanin; GlyA, glycophorin A; PE, phycoerythrin.