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.

心脏的原发性肿瘤并不常见；更罕见的是原发性心脏神经内分泌肿瘤。据我们所知，迄今为止只描述了两个病例，均为高级别肿瘤。我们报告了一个孤立的低级别心脏神经内分泌肿瘤，在一名 44 岁的男性在儿童时期有球囊瓣膜切开术史的右心室壁感染性细菌性心内膜炎的主动脉瓣修复期间意外发现。术中送去冰冻切片，结果显示为浆细胞样肿瘤。活检的最终病理显示肿瘤由粘性和不粘性的浆细胞样细胞组成，被血管网络和纤维化链分开。肿瘤显示出对 AE1/3、突触素和 CDX2 的强反应性，对嗜铬粒蛋白-A 和 CD56 有局灶反应性。²被看见了。进行了结肠镜检查并仅显示管状腺瘤。食管胃十二指肠镜检查无异常。在完全切除肿瘤后进行的 PET-CT DOTATATE 显示没有异常的放射性示踪剂摄取。患者目前状况良好，1 年后，并且报告没有可归因于类癌综合征或疾病进展的症状。该患者被内科肿瘤学分派进行年度随访和影像学检查，并被认为没有疾病证据。