Heart base tumours in dogs
Extra-adrenal paragangliomas are a diverse group of neuroendocrine tumours that may arise from multiple sites in the body. The paraganglia are made up of the adrenal medulla, chemoreceptors, vagal body and small groups of cells associated with the thoracic, intra-abdominal and retroperitoneal ganglia. They are classified into 3 groups phaeochromocytoma, extra-adrenal paragangliomas and chemodectomas. The most common heart base tumours are hemangiosarcoma of the right atrium, chemodectomas, ectopic thyroid tumours and ectopic parathyroid tumours. Chemodectomas are rarely invasive and slow to metastasize and therefore pericardiectomy is an option in these cases. Neoplasms of chemoreceptor origin occur primarily in dogs with infrequent occurence in cats and cattle.
Note in this case how the chemodectoma has entirely encompassed but not invaded the aorta.