BCL6 and mature T-cell and NK-cell non-Hodgkin lymphoma: AITL is one of the two most common PTCL subtypes (~36%) [2], the other being PTCL-NOS, and has been a focus of interest because the malignant cells express CD10 [3], PD-1, CXCR5 and BCL6 [4], all markers characteristic of the normal CD4+ T-cell subset, follicular helper (Tfh) T-cells, which are found in germinal centers.