Pollari M, Pellinen T, Karjalainen‐Lindsberg ML, et al. - In view of a previous finding of better survival in relation to high content of tumor‐infiltrating lymphocytes (TILs) and PD‐1 expressing TILs in testicular diffuse large B‐cell lymphoma (T‐DLBCL), researchers sought to further characterize distinct TIL subtypes as well as their proportions in association with patient demographics and survival. Experts found that TIL phenotypes differed substantially between the patients. Ki‐67⁺ and TIM‐3⁺ CTLs (cytotoxic T‐cells) were identified as the most prominent CD8⁺ TILs, whereas FoxP3⁺ regulatory T‐cells (Tregs) were recognized as the most prominent CD4⁺ TILs. Lower content of CTLs with activated or exhausted phenotypes was shown to be correlated with aggressive clinical characteristics. Besides showing significant variation in TIL phenotypes, findings of this study highlighted the adverse prognostic effect of Tregs in T‐DLBCL.