Splenic metastasis in a bitch affected by an ovarian dysgerminoma-A case report

Dysgerminomas are infrequent neoplasms resulting from undifferentiated germinal cells, mainly observed in the bitch. Our case describes for the first time a dysgerminoma related splenic metastasis in a bitch. A 14-year-old crossbred bitch was admitted at our facility with a 3-month history of irregular oestrous cycle, vulvar swelling, haemorrhagic vaginal discharge, lethargy and anorexia. Cytological examination showed the presence of superficial epithelial cells of the vaginal mucosa with a high degree of cornification. Vaginoscopy showed the typical pale and crenulated mucosal folds (oestrus). Haematological analysis indicated moderate anaemia and leukocytosis, and increased level of oestrogen. Ultrasound examination showed a mass located caudally to the kidney in the region of the right ovary. Abdominal and thoracic radiographs confirmed the findings and did not reveal metastases. Suspecting an ovarian tumour, we decided to perform a complete ovariohysterectomy. Once located, the right ovary presented an increased volume, irregular shape and reddish colour. Samples collected during the procedure were stained with haematoxylin and eosin and observed under optical microscope. The cells were characterized by a scant cytoplasm, a large vesicle type nucleus with coarsely granular chromatin and distinct cell borders. The neoplastic cells were remarkably similar to those of a testicular seminoma, allowing for the diagnosis of ovarian dysgerminoma. Two years after the ovariohysterectomy, the owner reported history of increased volume of the abdomen and lethargy. A second surgery was performed during which an irregular splenic mass was found. The morphological diagnosis was “splenic metastasis of dysgerminoma”. To the authors’ knowledge, dysgerminoma related splenic metastasis was never described in the bitch before.