Primary Ovarian Neuroendocrine Neoplasm With Carcinoid Syndrome and Carcinoid Heart Disease

<h3>Background</h3> Neuroendocrine neoplasms commonly arise in the midgut, lungs, or pancreas, while primary ovarian neuroendocrine neoplasms are rare and can present with carcinoid syndrome and carcinoid heart disease even in the absence of hepatic metastases. <h3>Case Report</h3> A 70-year-old female with coronary artery disease presented with 3 months of dyspnea, leg edema, diarrhea, and facial flushing. Examination suggested right-sided heart failure with a palpable lower abdominal mass. Her 24-hour urinary 5-hydroxyindoleacetic acid level was markedly elevated (106.0 mg), and serum chromogranin A was also elevated (468.6 ng/mL). Echocardiography showed severe tricuspid and pulmonic regurgitation from thickened, immobile leaflets. Imaging identified a DOTATATE-avid left adnexal mass on Gallium-68 DOTATATE positron emission tomography/computed tomography, consistent with primary ovarian neuroendocrine neoplasm. Preoperative management included long-acting octreotide, niacin, and guideline-directed heart failure therapy, followed by tumor resection. Histopathology confirmed insular-type ovarian neuroendocrine neoplasm without invasion or metastasis. Postoperatively, the patient improved clinically, and her biochemical markers normalized. <h3>Conclusion</h3> Primary ovarian neuroendocrine neoplasms can cause carcinoid syndrome and right-sided valvulopathy without liver metastasis, likely because ovarian venous drainage bypasses hepatic first-pass metabolism. Multidisciplinary care enables prompt diagnosis, preoperative stabilization, definitive resection, and coordinated surveillance.