A CASE OF PAPILLOMAVIRUS-ASSOCIATED TONGUE ADENOCARCINOMA IN A CAPTIVE WHITE RHINOCEROS

Papillomaviruses induce hyperplastic and tumoral lesions in different animal species4.We describe a case of Papillomavirus-Associated adenocarcinoma which occurred in a 41–year-old male white rhinoceros, maintained at the Zoological Garden of Pistoia, Tuscany3,5. The rhinoceros showed weight loss and difficulty in chewing the hay for three months before death2. At necroscopy, the most relevant finding was a lesion that involved the tongue, characterized by erosion of the mucosa with increased involvement of the dorsal surface. The cut surface showed lardaceous appearance with escape of purulent material. Histologically, the mass predominantly involved the submucosa and muscular portion of the tongue, resulting in closely packed large, medium, and small glands consisted of columnar cells without mucous cells. Tumor cells exhibited amphophilic to pale eosinophilic cytoplasm, high nucleo-cytoplasmic ratio and medium mitotic rate. No squamous differentiation was noted, and the squamous epithelium immediately adjacent to the adenocarcinoma showed slight perinuclear halos suggestive of PV-related changes. The tumor cells showed diffuse staining for A1-A3 pan-keratins, but staining for keratin 7 (CK7) clearly separated the adenocarcinoma from the adjacent non-neoplastic squamous epithelium. Keratin 19, keratin 20 and MUC-5AC were negative. Immunohistochemical staining performed with a monoclonal antibody against papillomaviruses evidenced a strong nuclear immunoreactivity only in glandular epithelium similarly to CK7. DNA extracted from paraffin-embedded tissue was tested by PCR using degenerated primers (FAP 59-64), amplifying common gene region of papillomaviral L11.The PCR result was an amplicon of 480 bp. Sequence similarity analysis with the BLAST tool of the National Center for Biotechnology Information and Papillomavirus Episteme tool showed that this fragments belongs to new putative PVs, not yet characterized for rhinoceros. To our knowledge this is the first case of Papillomavirus-Associated non-salivary gland-type adenocarcinoma arising in the base of the tongue in a captive white rhinoceros.