Figure 1: Sheets of non-keratinizing squamous carcinoma infiltrate fibrovascular tissue in this base of tongue biopsy specimen. The high nuclear to cytoplasmic ratio and the lack of keratinization are characteristic of human papillomavirus associated oropharyngeal squamous carcinoma (Hematoxylin and eosin) (A) .Chromogenic in situ hybridization for high risk human papillomavirus types illustrates the characteristic punctate pattern of positive staining in carcinoma nuclei (B).