T-cell immunoreceptor with Ig and ITIM domains (TIGIT) is extensively expressed in the microenvironment of nodular lymphocyte-predominant Hodgkin lymphoma and T-cell-/histiocyte-rich large B-cell lymphoma.

T-cell immunoreceptor with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains (TIGIT) is a molecule involved in the immune escape of tumour cells and is a target of immunotherapy. Recently, TIGIT has gained attention as a crucial player in the tumour microenvironment (TME) of lymphomas. TIGIT immunohistochemical expression has not been thoroughly studied in nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and T-cell-/histiocyte-rich large B-cell lymphoma (THRLBCL). We studied TIGIT's immunohistochemical expression in 27 whole-lymph-node sections from 19 patients diagnosed with NLPHL and eight patients diagnosed with THRLBCL. TIGIT was consistently expressed in the TME of all lymphomas, exhibiting strong membranous staining. The TME expression ranged from 40% to 90% (median 70%). Rosettes around tumour cells were common in 23 (85.1%) cases. TIGIT was expressed by tumour cells in four cases (14.8%). NLPHL and THRLBCL harbour ​extensive TIGIT expression in their microenvironment, often in the form of peritumoural rosettes; some express TIGIT in tumor cells. Despite a small cohort, our results suggest that patients may benefit from TIGIT inhibition.