Human papillomavirus-16 associated adenocarcinoma NOS of base of tongue

Abstract

The causative role of human papillomavirus (HPV) in a subset of squamous cell carcinomas of the oropharynx (OSCC) is now well established with HPV-16 being detected in approximately 92% of HPV-positive OSCC in North America. Recently HPV has also been found in some non-squamous oropharyngeal carcinomas including adenosquamous carcinomas, neuroendocrine carcinomas, and undifferentiated "lymphoepithelioma-like" carcinomas. Herein, we report a HPV-16 positive adenocarcinoma NOS arising in the base of the tongue of a non-smoker, 64 year-old male. To our knowledge, this is the first time this association has been clearly documented. The adenocarcinoma was diffusely positive for p16 and HPV-16 was demonstrated by in situ hybridization and linear array analysis. Q-PCR demonstrated a viral load of 4 copies per cancer cell, whereas qRT-PCR for E6/E7 transcript levels were 30 copies per 1,000 human ribosomal protein large P0 (RPLP0) reference gene. The presence of HPV in non-squamous oropharyngeal carcinomas raises the possibility that HPV is also involved in the carcinogenesis of some uncommon carcinomas of the region.

Fig. 1

Axial T2 weighted images with fat saturation demonstrate a mildly hyperintense mass involving the left tonsil with contiguous extension along the left tongue base (arrows). Sagittal T2 weighted image shows the component of tumor along the tongue base (long arrow) and the continuous disease extending onto the vallecula (short arrow)

Fig. 2

Adenocarcinoma involving the surface of the base of the tongue. Note the remaining normal crypts and lymphoid component (×16) (a). Surface involvement demonstrating the transition from adenocarcinoma to non-neoplastic squamous epithelium. The squamous epithelium shows perinuclear halos reminiscent of koilocytes (×200) (b). The adenocarcinoma was composed of back-to-back glands with scanty intervening stroma. The glands were lined by columnar cells with pseudostratified nuclei (×100) (c). The tumor was diffusely positive for CK7 (d). Tumor showing diffuse nuclear and cytoplasmic staining for p16 (×100) (e). In situ hybridization for HPV16 showing coarse nuclear signal indicative of high-copy number (×200) (f)