CT of the thorax – A large non-uniformly enhancing mass of approximately 4.5 cm diameter is obstructing the right atrium and auricular appendage. A large tumor thrombus extends 4 cm into the cranial vena cava and 2 cm into the azygos vein. The cranial vena cava is expanded at 1.5 cm level with the tumor thrombus and dilated at 2 cm cranial to it. The brachycephalic and jugular veins are dilated as well as the ventral vertebral venous sinus. The marked vertebral venous sinus dilation causes a bilateral mass effect on the floor of the vertebral canal within the ventral epidural space and significant spinal cord compression. 

The caudal vena cava presents mild dilation at 1.8 times the aortic diameter. The right venricle is compressed. There is moderate bilaterally symmetric pleural effusion and mild hydrostatic atelectasis of the lung. Scant pericardial and peritoneal effusion is noted as well as a gallbladder wall edema and mild generalized hepatomegaly with dilation of the hepatic veins. The lung parenchyma and mediastinal lymph nodes are negative for metastatic spread. The sternal lymph node presents mild reactive hyperplasia. The spleen is volume contracted and negative for metastatic spread.