TRBC1 and mature T-cell and NK-cell non-Hodgkin lymphoma: When the T- and B-lymphocyte screen tubes were negative, an additional tube with a combination of TFH markers (PD-1 and CD10) and some pan-T cell antibodies (such as CD3, CD4, CD5, CD7, and CD8) was added to confirm or exclude a supposed PTCL diagnosis, and for patients with an equivocal clinical history or immunophenotyping, TRBC1 was added to this tube to determine the clonality of the T cells.