BCL6 and mature T-cell and NK-cell non-Hodgkin lymphoma: Except for PTCL-NOS, AITL is the most common subtype of PTCL (21–36.1%) (Chiba and Sakata-Yanagimoto, 2020; de Leval et al., 2015) and is believed to arise from a subset of peripheral mature CD4+ T-cells corresponding to T-follicular helper (TFH) cells, characterized immunophenotypically by expression of a set of cellular markers like PD1, CXCR5, BCL-6, CD10, CXCL13, and ICOS-1 (Attygalle et al., 2002; Chiba and Sakata-Yanagimoto, 2020; Dupuis et al., 2006; Marafioti et al., 2010; Mourad et al., 2008).