Endocrine Abstracts

Introduction: Cardiac paragangliomas are rare endocrine neoplasms. Surgical resection is first line treatment. Here, we describe a case of cardiac paraganglioma where surgical resection was aborted due to involvement of important cardiac structures. Systemic therapy was instead pursued with tyrosine kinase inhibitor cabozantinib.

Case: A 64-year-old man with a past medical history significant for tobacco use and poorly controlled type 2 diabetes mellitus presented with chest pain, several months of progressive fatigue and 15 pound unintentional weight loss. Echocardiogram revealed a 6.9×5.8×4.9 cm right-sided cardiac mass. Biopsy was performed demonstrating cytopathology consistent with paraganglioma. Laboratory studies revealed chromogranin A 1,038 ng/ml (normal <93 ng/ml), plasma normetanephrine 1.87 nmol/l (0–0.89 nmol/l) and plasma metanephrine 0.14 nmol/l (0–0.49 nmol/l). Ga-68 DOTATATE Positron Emission Tomography/Computed Tomography (PET/CT) scan revealed DOTATATE avidity within the region of the cardiac mass. No additional lesions or metastatic foci were identified. Next-generation sequencing performed on the tissue biopsy demonstrated an SDHB mutation (H244D) at a variant allele frequency of 62.2%. Surgical resection was attempted and aborted due to the paraganglioma encasing the right coronary artery and the tricuspid valve. Systemic therapy was initiated with tyrosine kinase inhibitor cabozantinib. Dose reduction was required due to development of palmar-plantar erythrodysesthesia. Subsequent surveillance Ga-68 DOTATATE PET/CT scan revealed partial response to treatment at two months with increasing central photopenia of the cardiac mass from 94 standardized uptake value (SUV) to 54 SUV. The patient had biochemical response with decreasing chromogranin A and norepinephrine levels.

Conclusion: Treatment of cardiac paraganglioma ideally consists of local resection, however this is not always possible due to involvement of critical structures of the heart. Systemic therapy for paragangliomas is largely based on small, retrospective studies. Our case illustrates an unresectable cardiac paraganglioma with response to cabozantinib as evidenced by radiologic and biochemical data. Radionucleotide therapy is a potential future treatment option for this patient.