p16 immunostaining of metastatic HNSCCs showing the distribution of staining by tumor origin and as a function of HPV ISH. Each star (p16 staining) and corresponding circle (ISH) represent results from individual FNA/biopsy samples. Superimposed symbols reflect concordant results, whereas nonoverlapping symbols (double-sided arrows) reflect discordant results. In 5 cases, p16 staining was performed alone without corresponding ISH analysis. p16-positive metastases tended to be from the oropharynx and tended to be HPV positive by ISH.