SUN-014 Primary Ovarian Neuroendocrine Neoplasm with Carcinoid Syndrome and Carcinoid Heart Disease: A Case Report

Abstract Disclosure: K. Thammakosol: None. P. Vathesatogkit: None. S. Leelasithorn: None. C. Sriphrapradang: None. Background: Neuroendocrine neoplasms (NENs) typically arise in the midgut, lungs, or pancreas, while primary ovarian NENs are very rare. Unlike gastrointestinal NENs, ovarian NENs can uniquely present with carcinoid syndrome and carcinoid heart disease in the absence of liver metastases, making them a distinct clinical entity. Case Presentation: We report the case of a 70-year-old woman with a history of coronary artery disease, controlled hypertension, and hypercholesterolemia who presented with a 3-month history of exertional dyspnea, bilateral leg edema, diarrhea, and facial flushing. Examination revealed a plethoric face, jugular venous engorgement, a pansystolic murmur over the tricuspid valve, a diastolic blowing murmur over the pulmonic valve, bilateral leg edema, and a palpable 10 cm mass in the left lower abdomen. Laboratory investigations showed significantly elevated 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA; 106.0 mg/day, normal: 2-9 mg/day) and serum chromogranin A (468.6 ng/mL, normal: 0-76.3 ng/mL). Transthoracic echocardiography demonstrated thickening and restricted motion of the tricuspid valve and pulmonic valve leaflets, causing severe non-coaptation with significant tricuspid regurgitation and severe pulmonic regurgitation with relative pulmonic stenosis. Abdominal computed tomography revealed a 7.8 x 11.8 x 9.0 cm heterogeneous enhancing left adnexal mass, which was DOTATE-avid on Gallium-68 DOTATE PET/CT, confirming a primary ovarian NEN. The patient was diagnosed with a primary ovarian NEN complicated by carcinoid syndrome and carcinoid heart disease. Preoperative management included long-acting somatostatin analog therapy (octreotide long-acting release 30 mg intramuscularly every 4 weeks), niacin supplementation, and management of right-sided heart failure. Two months later, she underwent a successful hysterectomy with bilateral salpingo-oophorectomy for complete tumor resection. Pathology confirmed an insular-type ovarian NEN with a Ki-67 index < 1%, and no evidence of ovarian surface involvement, lymphovascular invasion, or lymph node metastasis. Postoperatively, the patient experienced significant symptom resolution, including improvement in right-sided heart failure, diarrhea, and flushing, with normalization of 24-hour urine 5-HIAA (3.3 mg) and serum chromogranin A (18.3 ng/mL). Conclusions: This case highlights the importance of recognizing ovarian NEN as a rare but significant cause of carcinoid syndrome and carcinoid heart disease, even in the absence of liver metastases. It also underscores the critical role of multidisciplinary management in achieving optimal outcomes. Presentation: Sunday, July 13, 2025