Primary cardiac malignant peripheral nerve sheath tumour in a dog

A 6‐year‐old, female labrador retriever was presented for acute onset abdominal distention. Clinical examination identified tachycardia, a novel grade 3/6 right basilar systolic cardiac murmur, a distended abdomen and ventral pitting oedema. Jugular pulses were not present. Echocardiography revealed an infiltrative, intramural cardiac mass, with partial occlusion of the right atrium and ventricle, resulting in isolated caudal vena cava syndrome. Postmortem examination revealed a large mass arising from the base of the right atrium and extending into the ventricular lumen. Histopathological and immunohistochemical findings were consistent with a diagnosis of malignant peripheral nerve sheath tumour, a rare primary cardiac neoplasm in dogs.