PDCD1LG2 and cancer: In contrast to his liver metastasis, the in situ carcinoma had a lower tumor mutational burden, lacked programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2) amplification and had a distinct PTCH1 mutation, suggesting that the in situ BCC of his skin and the metastatic BCC of his liver were derived from different clones of cells.