Unsupervised HC of PTCL cases. (A) ALCL cases formed 2 distinct clusters (major and minor HC clusters) with respect to AITLs and PTCL-NOS. ALK(+) ALCL and ALK(–) ALCL cases were interspersed with each other. A group of miRNAs highly expressed in ALCL cases is highlighted (yellow box) and listed on the right side (red bar). A strong stromal signature is represented by the blue bar. (B) miRNA signature associated with ALCL (vs AITL and PTCL-NOS). The Bayesian classifier included 28 miRNAs. Most of the cases in the ALCL minor hierarchical cluster were in the intermediate group. Yellow boxes highlight the minor ALCL group. (C) miRNA signature associated with ALK(+) ALCL. A 7-miRNA classifier was derived by using the Bayesian algorithm, and it included 5 upregulated and 2 downregulated miRNAs. Orange box highlights the expression of this signature among CD3⁺ normal T cells, stromal cells, and ALCL cell lines. (D) miRNA signature associated with ALK(–) ALCL. An 11-miRNA classifier included 4 upregulated and 7 downregulated miRNAs. Orange box highlights the comparative analysis of this signature in CD3⁺ normal T cells, stromal cells, and ALCL cell lines. LOOCV, leave-one-out-cross validation; NC, not classifiable.