Figure 2.

Current thyroid tumor classification based on cancer cell characteristics (A) and potential classification approach based on immune phenotype (B). Classical classification takes into account cell origin, morphology, mutational status, altered molecular pathways, TNM stage, and signature of the tumor. The specific interaction between tumor and immune system determines the tumor immune phenotype. ATC-like tumors, presenting T cell infiltration both in the tumor center and in invasive margin or only in the tumor center, have a hot or altered immunosuppressed phenotype. Conversely, PDTC-like tumors have a cold or an altered immunoexcluded phenotype, with not or poor T cell infiltration only at invasive margin.