FCM and TCR γ gene rearrangement analysis in LGL leukemia. (A) FCM analysis of a typical case of T CD3⁺ LGL leukemia showing CD3⁺/CD5^dim/CD8⁺ (dark green). (B) FCM analysis of a case of NK CD3⁻ LGL leukemia showing a CD3⁻/CD8⁻/CD16⁺/CD56⁺ phenotype (pink). KIR monotypic expression using CD161 and NkB1. (C) Clonality assessment: specific Vβ mAbs showing restricted expression of Vβ13.1 >90% (left); detection of clonal TCR γ gene recombination by gene scanning analysis, showing single peak in green (right). (D) Stat 3 mutation detection in a case of T-LGL leukemia using Sanger sequencing. FCM, flow cytometry; WT, wild-type.