Primary ovarian leiomyosarcoma in a dog - case report

ABSTRACT Leiomyosarcoma is the most common malignant mesenchymal tumor found in the retroperitoneal and intra-abdominal regions, while its ovarian location is considered rare in bitches and is scarce in the literature due to its underdiagnosis. A 12-year female dog of no defined breed was seen presenting with an increase in volume in the right flank region and tenderness on palpation caudal to the last right rib. Considering the suspicion of an abdominal neoplasm, the patient underwent ultrasound, which detected the presence of a heterogeneous mass in the right ovary. For diagnostic purposes, an exploratory celiotomy was performed, in which the 18x15x8cm mass was excised and sent for histopathological analysis. Multiple cysts were detected in the left ovary and pyometra in both uterine horns. Histopathological examination showed non-encapsulated neoplastic proliferation, composed of mesenchymal cells, neoplastic cells with indistinct cytoplasmic boundaries, eosinophilic fibrillar cytoplasm, oval or fusiform nuclei, finely granular chromatin and a single conspicuous nucleolus, making the diagnosis highly compatible with leiomyosarcoma in the right ovary. To confirm the histogenesis, the IHC technique was used. As a result, complementary tests become essential tools for better diagnosis and correct therapy in these disorders, as they present specific clinical signs.