High-risk human papillomavirus associated squamous cell carcinoma

(A) High-risk HPV associated squamous cell carcinoma. A base of tongue tumor, predominantly nonkeratinizing, composed of tumor nests with peripheral palisading and central, small tumor cells without much cytoplasm.

(B) A p16 immunostain demonstrating uniform and diffuse staining of both nuclei and cytoplasm that characterizes a positive reaction. Less than 70% positivity is regarded as negative. A positive stain for p16 is interpreted as a surrogate for the presence of high-risk HPV.