PDCD1LG2 and melanoma: A panel of representative immune markers was tested by immunohistochemistry on melanoma biopsies from the training set, including PD-L1 and PD-L2 (included as surrogates of inflammed tumors and tumor immune escape), β-catenin (chosen as tumor pathway driving immune-suppressed microenvironment), CD8 (as marker of antitumor effector T cells) and CD163 (recapitulating tumor associated myeloid cells including macrophages).