[Metastatic seminoma in the orbital region in a dog - case report]

ABSTRACT Seminoma is a testicular neoformation originating from germ cells, commonly occurring in dogs. With higher prevalence in senile animals, the biological behavior of canine seminomas generally benign. This case reports seminoma with mestastasis in the orbital region in a 14-year-old dog. The animal was treated with a complaint of increased volume in the left orbit, and later a nodule in the testicle was discovered. Fine-needle aspiration of the orbit mass initially indicated a high-grade lymphoma. The definitive diagnosis of diffused seminoma was established by histopathological examination, resulting in poorly differentiated malignant neoplasia. Finally, the diagnosis was confirmed through immunohistochemistry, being the result compatible with diffused seminoma. Metastatic seminomas reported in dogs are quite uncommon. In this work we report a case of diffused anaplastic seminoma in dogs, where the main focus of metastasis was observed in the orbital region, and we also describe and discuss the difficulties encountered in the diagnostic.