Patient 5 had tongue cancer with bone metastasis after surgery, increased [18F]F-FDG metabolism was detected in the left side of the sacrum, there was a slight increase in [68Ga]Ga-HN11-1 uptake in this area, suggesting potential PD-L2 expression in the metastatic lesion. This evidence concerns the gene PDCD1LG2 and bone metastasis.