A Canine Case of Primary Intra-Right Atrial Paraganglioma

Abstract

An 11-year-old mixed breed dog was presented with signs of anorexia. Radiographic and ultrasound examinations revealed a large mass in the heart, between the right atrium and the right ventricle. Upon gross inspection, a multilobulated tumor arising from the right atrial wall and occupying the right atrium was identified. Microscopical analysis demonstrated that this tumor consisted of neoplastic cells with granular cytoplasm, which were separated into nests by fine fibrovascular stroma and were negative for Grimelius’s method. Immunohistochemical examinations revealed that the neoplastic cells expressed chromogranin A, synaptophysin and neuron specific enolase. Electron microscopy revealed that the cytoplasm of the neoplastic cells held secretory granules. Based on these pathological findings, the tumor was diagnosed as a paraganglioma. This report is a rare case of primary paraganglioma deriving from the right atrium and provides a detailed characterization of its morphological features.

A descriptive review of cardiac tumours in dogs and cats

“…This dog was euthanized hence no further outcome information was available, but electron microscopy showed numerous neurosecretory granules within the cytoplasm of the neoplastic cells, hence supporting the suspicion of a functional tumour. A similar report has described a case of a functional paraganglioma which stained positive for chromogranin indicating a neuroendocrine origin. Intracardiac metastases of an aortic body tumour have also been described in one dog, but metastases from these lesions seem uncommon.…”

Pheochromocytomas and paragangliomas in humans and dogs

“…In line with this, extended invasion of the caudal vena cava beyond the hepatic hilus was associated with a higher post‐operative mortality rate, but did not affect long‐term prognosis . The only possible treatment of PGL in dogs is surgery and its success greatly depends on the localization of the tumour …”

“…Canine PCC are relatively large tumours, with an average diameter of 5.1 cm (1.1–15 cm) at diagnosis . PGL tend to be slightly larger, with an average diameter of 6 cm (2.7–16 cm) . Most PCC in dogs are unilateral; about 10% are bilateral.…”

“…In humans and dogs, diagnosis of PCC and PGL is supported by immunohistochemistry using several markers, including chromogranin A (CrA), synaptophysin (SYP) and neuron‐specific enolase (NSE) which stain the chromaffin cells, and S100, which is specific for the sustentacular cells . The markers have high sensitivity for diagnosing PCC, but not for diagnosing PGL (Table ).…”

Radiation therapy for non‐resectable neuroendocrine tumour in two dogs

“…Sites of metastasis include lungs, regional lymph nodes, liver, pancreas and kidneys 2,3 . Metastasis to the mediastinum, atrium, retroperitoneal space, spinal cord and bones have also been reported, with an apparent predisposition for the vertebrae 1,2,7–12 . CBTs are usually located near the bifurcation of the common carotid artery in the cranial cervical area.…”