Although the primary malignancy cannot be ascertained here it appears to be more likely that the adrenal mass is the primary tumor with secondary seeding to the liver
parenchyma. Possible differential diagnoses include adenocarcinoma (which is not
necessarily functional), pheochromocytoma or other secondary neoplasia.
Surgical removal of the tumor would require venotomy of the caudal vena cava. The
mortality rate of this procedure has been reported to be at 22 % and does not
necessarily differ from the mortality rate in adrenal tumors without thrombi (Kyles et
al. Surgical management of adrenal gland tumors with and without associated tumor
thrombi in dogs: 40 cases (1994–2001), JAVMA 2003). But the overall prognosis is
poor because of the multifocal distribution of the malignancy.
Confirmation of diagnosis would warrant sampling, which may be done under
ultrasound guidance for both the adrenal tumor and the liver mass/nodules. Full tumor
staging would further require 3 view chest radiographs and cursory echocardiographic
examination to rule out heart base masses.