Fibrosarcoma in Rottweiler dog: case report

Abstract

The present study aims to report a case of fibrosarcoma in an elderly canine patient who underwent necroscopic examination in June 2018 after natural death. Macroscopic and microscopic analyzes of the pathological findings were performed by organ visualization and histopathological processing of the collected samples. Macroscopically, a pelvic tumor mass of approximately 15 cm, cardiac hypertrophy with parasites in the ventricular lumen, congested and nodular lungs, hepatomegaly and renal atrophy were observed. Histological analysis of the primary tumor mass was compatible with a fibrosarcoma, with most cells of fusiform morphology, with foci of hemorrhage and necrosis in the center of the tumor, alternating with regions of desmoplastic reaction, nuclear atypia and prominent nucleoli. Also, microscopy revealed swollen pulmonary parenchyma with diffuse hemorrhage, vascular congestion, thickening of the alveolar septa and pulmonary nodules suggestive of metastatic lesions, as well as liver with congested sinus capillaries and diffuse hemorrhage in the hepatic parenchyma with foci of coagulation necrosis. Fibrosarcoma is a tumor of mesenchymal origin, composed of transformed fibroblasts, in a collagen background. It occurs in all species, but is more common in dogs and cats. In dogs, it usually manifests in solitary form and in older individuals, with a mean age of 9.7 years. Most pathologists describe the histological picture of fibrosarcoma as a fishbone pattern. It is usually a very invasive tumor, making surgical treatment difficult because it does not allow a wide margin of excision, and its clinic manifests itself late, making diagnosis and treatment even more difficult, as in the case reported here, in which the patient suddenly died. Thus, histopathological and cytopathological analysis remain the gold standard among the initial diagnostic methods to confirm the presence of the tumor, highlighting the importance of applying these study methods in determining the morphological characteristics of different types of lesions, as well as their forms, whose diagnosis can be confirmed with other diagnostic methods.