Cytologic evaluation of p16 staining in head and neck squamous cell carcinoma in CytoLyt versus formalin-fixed material.

The fixative used had a drastic impact on p16 staining, which explained the staining variability reported in the literature. FFCBs show a diffuse staining pattern, which correlates with HR-HPV status, whereas CCBs show a weaker and inconsistent staining pattern, which is more difficult to interpret.