Primary cardiac low-grade neuroendocrine tumor: a case report and review of the literature.

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 mm2 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, 1 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.