Fig. 2.

Although the majority of OPSCCs stained using p16 immunohistochemistry are either categorically positive (see Fig. 1a, b) or negative (see Fig. 1d), equivocal staining patterns are occasionally encountered in clinical practice: a–d Show equivocal p16 staining, highlighting the problem of empirically defined cut-offs for HPV-driven p16 overexpression