A very rare granular cell tumor that arises from the heart. The disease is cardiac granular cell neoplasm (MONDO_0003254). Also known as: Cardiac granular cell neoplasm, Cardiac granular cell tumor, Cardiac granular cell tumour, granular cell neoplasm of heart, granular cell neoplasm of the heart, granular cell tumor of heart, granular cell tumor of the heart, granular cell tumour of heart.