Ovarian Dysgerminoma in a Dog
World Small Animal Veterinary Association World Congress Proceedings, 2009
M. Faustino1; M.S.F. Talib1; L.N. Torres2; C.M. Oliveira1
1Gynecology and Obstetrics Clinic of the Veterinary Hospital (FMVZ--University of São Paulo), Brazil; 2Animal Pathology Section of the Veterinary Hospital (FMVZ--University of São Paulo), Brazil

Dysgerminomas are extremely rare tumors in domestic animals, as well as teratomas and teratocarcinomas. They are originally derived from fertilized mammalian ovum, which has an overall differentiation capability to generate embryonic tissue. Therefore, they are classified as germ cell tumors. Its correspondence in male sex tumors is represented by testicular seminomas. The present case report refers to a XX-year-old intact Poodle bitch presented at the Gynecology and Obstetrics Clinic of the Veterinary Hospital (FMVZ--University of São Paulo) with a complaint of recent sanguineous vaginal discharge for 1 month, with unremarkable general committal. On diagnostic tracing, transabdominal ultrasound revealed a hypoechoic neoplastic structure of 11,5 x 5,3cm in medial hypogastric area with irregular outline containing cystic areas. In addition, at the right kidney region, caudally, an irregular and heterogeneous mass of 3,6 x 2,1cm was visualized, consistent with ovarian tumor. Exploratory laparotomy identified the larger mass as uterine neoformation of inner growth. The smaller mass presented at the anatomic area of the right ovary, internalized by the ovarian bursa as a replacement of the overall gonad. The patient underwent bilateral ovariohysterectomy. There was no such macroscopic evidence of metastasis in the peritoneal cavity. Histologically the ovarian tumor presented as proliferative neoplastic germ cells in solid islands with no peculiar arrangement. This referred cells had large and marked nucleolus and rare eosinophilic cytoplasm. A high mitotic potential was identified. A sage fibrovascular stroma and foci of necrosis were inserted by neoplastic cells, histologically defined as dysgerminoma. Dysgerminomas are composed by a uniform, solid and irregular cell population. The uterine mass was histologically identified by a rare lymphangiectasia and glandular cystic dilation with no inflammatory or metastatic evidence. The uterine diagnosis was established as endometrial cystic hyperplasia concurrent to an ovarian tumor. By the time of her fourth month postoperatory, several metastatic foci were noted through abdominal ultrasonography. Metastasis is reported to occur in 10 to 30% of cases and the main sites are abdominal lymph nodes, liver, omentum, pancreas, kidneys and adrenal glands. The treatment of choice remains the surgical removal by ovariohysterectomy.

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M. Faustino
Gynecology and Obstetrics Clinic of the Veterinary Hospital
FMVZ – University of São Paulo

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