Endocrine Abstracts

JOINT3554

Introduction: Neuroendocrine tumours (NETs) are rare and more frequently metastasize to the abdominal lymph nodes or liver. Extra-abdominal metastases are now increasingly detected due to ⁶⁸Ga-SSA-PET/CT’s high sensitivity. Right sided valvular dysfunction is the hallmark of carcinoid heart disease (CHD) caused by high serotonin levels secreted by liver metastasis. Cardiac metastases (CMs) are rare, occurring in about 1-4% of NETs, primarily from small intestine. They can occur in association with typical valvular involvement or may be the only manifestation of CHD. Patients may be asymptomatic or presenting with nonspecific symptoms depending on tumour location and burden.

Case: 66-year-old-male, presenting with abdominal distension, diarrhea and weight loss. Underwent right hemicolectomy due to a tumour in the terminal ileum detected on colonoscopy. Histopathology revealed G2 NET (2 mitoses/10 HPF), pT4N0 LVI2 R0. Abdominal-pelvic CT showed no abnormalities; ⁶⁸Ga-SSA-PET/CT revealed focal uptake in the apical region of the left ventricle, initially not considered significant. 1-year post-surgery, developed diarrhea, flushing and weight loss. Second evaluation with ⁶⁸Ga-SSA-PET/CT continued to show myocardial uptake and identified mesenteric densification, raising suspicion of lymph node involvement. Cardiac MRI (CMR) revealed an intramural cardiac mass (12x25mm) near the apex without cleavage plans from myocardium, interfering with wall motion and suggestive of a rhabdomyoma or cardiac lymphoma. The patient was referred to our center, with chromogranin A (CgA) 703.9 ng/ml (≤102), on PPI, 5-hydroxyindoleacetic acid (5-HIAA) 5.6 mg/24h (≤15) and normal B-type natriuretic peptide. ECG revealed sinus rhythm and complete left bundle branch block. Transthoracic echocardiogram showed no evidence of CHD but demonstrated increased left ventricular wall thickness (apical septal segment), with localized reduced contractility. Using Sonovue contrast we observed the referred mass. A 24h ECG monitoring didn`t show significant arrhythmias. The patient had no cardiac symptoms. Based on integrated clinical assessment, CMR was revised and the mass reclassified as a CM from the known NET; cardiac biopsy (considered high-risk) was not performed and surgical intervention was not performed due its unresectability. Lanreotide 120 mg was initiated with improvement of abdominal symptoms and CgA. At 12 months, contrast echo and CMR continue to show stable intramyocardial mass.

Conclusions: CMs from NETs are rare and typically found in advanced disease. In this case, the heart was the first site of distant metastasis. Multidisciplinary discussion enabled clinical diagnosis and appropriate therapy. Despite the usual aggressive nature of other CM, NETs often have an indolent course with prolonged survival.