Epidemiological and pathological aspects of hemangiosarcoma in dogs from the Central Region of the State of Rio Grande do Sul, Brazil. Out of the studied cases (n=40), aged dogs (72.2% of the cases) and dogs of German shepherd breed (20% of the cases) were clearly more frequently affected since in the total population of necropsied dogs in the same period (n=7,063) this age group and breed were comparatively less represented (respectively 14.6% e 10.1% of the cases). At necropsy (n=40) most tumors (92.5%) occurred as nodules and less frequently as masses (37.5%), affecting mainly the spleen (62.5%), lung (60%), liver (52.5%), peritoneum (42.5%), kidney (37.5%), brain (30%), pleura (25%), and heart (22.5%). Hemoperitoneum (42.5% of the cases) and resultant anemia (22.5% of the cases) were also observed. On histological examination (n=25), most hemangiosarcomas (84%), were, in general, well differentiated, of low grade (64%) and possessed a scant stroma (84%), although frequently (68%) focal areas with cells displaying some degree of atypia were seen. Necrosis, hemorrhage, and thrombosis were observed in all cases, however extramedullary hematopoiesis (28%) and benign angiomatous proliferation (12%) were less common findings. In all cases submitted to immunohistochemistry staining (n=24) the tumor cells displayed a finely granular positive staining when using anti-factor von Willebrand. Regarding anatomical classification, 55% of the hemangiosarcomas were considered as multicentric, 30% as primary tumors with one or more metastasis and 15% were solitary tumors. This paper discusses these results an suggests, based on the combination of affected organs, a scheme for setting apart primary hemangiosarcoma with metastasis from multicentric hemangiosarcoma, aiming to uniformize communication between pathologists regarding this tumor.
Diseases of dogs; oncology; neoplasms; multicentric tumors; hemangiosarcoma
