Primary tumors of the heart are uncommon; even rarer are primary cardiac neuroendocrine tumors. To our knowledge, only two cases have been described to date, both being high-grade tumors. We report a solitary low-grade neuroendocrine tumor of the heart, unexpectedly discovered during aortic valve repair for infectious bacterial endocarditis on the wall of the right ventricle in a 44 -year-old man with a history of balloon valvulotomy as a child. Frozen section was sent intraoperatively and demonstrated a plasmacytoid neoplasm. Final pathology of the biopsies showed a tumor composed of both cohesive and discohesive plasmacytoid cells separated by a vascular network and strands of fibrosis. The tumor showed strong reactivity for AE1/3, synaptophysin, and CDX2 with focal reactivity for chromogranin-A and CD56. Neither necrosis nor a mitotic rate of greater than 2 mitoses per 2 mm was seen. A colonoscopy was performed and demonstrated only a tubular adenoma. An esophagogastroduodenoscopy was unremarkable. PET-CT DOTATATE, performed after complete resection of the tumor, demonstrated no abnormal radiotracer uptake. The patient continues to do well at present, one year later, and reports no symptoms attributable to carcinoid syndrome or disease progression. The patient was assigned by medical oncology to yearly follow-up and imaging, and is considered to have no evidence of disease.Copyright © 2021. Published by Elsevier Inc.