Treatment of intranasal transmissible venereal tumor (TVT) with combined radiotherapy and chemotherapy: a case report

Abstract

Transmissible venereal tumor (TVT) in dogs is a malignant tumor transmitted as a result of transplantation of tumor cells. In males and females, it is most commonly seen in the external genitalia as cauliflower-like growths. However, extragenital localization has also been reported. In cases of extragenital TVT, if there is no lesion in the genital organs, differential diagnosis should be made with histiocytoma, lymphoma, poorly differentiated mast cell tumors and amelanotic melanomas. Although surgical excision is not preferred in the treatment, chemotherapy protocols are used, while treatment with radiotherapy is also effective. The case consists of a male Siberian Husky dog, aged seven years and seven months who had symptoms of unilateral nasal hemorrhage and was referred to our clinic with the suspicion of nasal carcinoma as a result of diagnostic investigations that lasted for 5 months in another country. In the clinical examination of the patient, unilateral hemopurulent nasal discharge, reverse senezing and exercise intolerance were observed. Due to the inconsistency in the clinical course of the patient who was referred with the suspicion of possible carcinoma, clinicopathological consultation was made to Istanbul University-Cerrahpaşa Faculty of Veterinary Medicine, Department of Pathology. In order to determine the differential diagnosis, prognosis and appropriate treatment approach, immunohistochemical marking was performed with vimentin, pancytokeratin, CD3, CD79a, chromaogranin, NSE and lysozyme antibodies using the Streptavidin-Biotin method. The patient was diagnosed with TVT histopathologically and immunohistochemically, and after premedication, a weekly session of Vincristine sulfate at a dose of 0.6mg/m2, a total of recommended 6-8 weeks of chemotherapy session was targeted. However, as a result of severe neutropenia attacks after vincristine sulfate administration, radiotherapy was added to the treatment protocol. In total, 1500 cGy radiation therapy was applied in 5 fractions. During this period, the clinical symptoms of the patient decreased and an increase in body weight was observed. We think that the case with a rare diagnosis of intranasal TVT and the combined radiotherapy and chemotherapy treatment without any relapse after treatment contributed to veterinary oncology.