Example of the STA and gating strategy applied to FNA in a follicular lymphoma (case 11) acquired on a FACSCanto II flow cytometer (BD Biosciences). 7-AAD-negative cells (orange) were gated in order to exclude dead cells. FSC-W^low/CD45⁺ events were gated to define the leukocyte area and to exclude glued cells (doublets; green). Gated cells were examined in the SSC/CD45 diagram for the identification of lymphocyte clusters (gray). A region drawn on (CD19+CD20)⁺/CD3^- events identified the B cells (blue) and allowed the analysis of surface light chains and CD5 and CD10 expression on B lymphocytes. A region drawn on CD3⁺/(CD19+CD20)^- events identified T cells (purple) and allowed the quantification of CD4 and CD8 subpopulations and CD5 expression. CD3^-/(CD19+CD20)^- events (non-T/non-B) were considered to be NK cells. The ratio of FSC-A signal distribution between B and T lymphocytes was used to evaluate B-cell size. Population hierarchy (bottom right). Gating on B cells displayed polyclonal and surface light chain-negative elements corresponding to CD10⁺ events (red; 25% of the total lymphocytes). FSC-A = Forward-scatter area; FSC-W = forward-scatter width; SSC-A = side-scatter area.