MON-036 An Unusual Case of Catecholamine-Secreting Carotid Body Paraganglioma

Abstract Disclosure: N. Hernandez: None. G.Y. Kim: None. Background: Paragangliomas (PGLs) are neuroendocrine tumors from chromaffin tissues in sympathetic or parasympathetic ganglia. Head and neck PGLs (HNPGLs) comprise 3% of all PGLs with an incidence of 0.6 cases per 100,000 persons-years. The clinical presentation of PGLs is variable and depend on their location. Although typically asymptomatic, carotid body and vagal PGLs can present as a painless neck mass associated with dysphagia, cough, or hoarseness. HNPGLs are not commonly associated with catecholamine hypersecretion, as up to 95% are non-secretory. Diagnosis is established by anatomical localization of the tumor. Even though catecholamine secretion is rarely found with HNPGLs, biochemical testing should be done to rule out a secretory component. We present a case of a patient with bilateral carotid body PGL with unilateral catecholamine hypersecretion. Clinical Case: 38-year-old woman without significant medical or family history was seen in endocrinology clinic in 2019 with symptoms of daily right sided headache lasting for a few minutes, associated with nausea, sweating and hiccups. These episodes were triggered by positional changes of the neck. MRI revealed a T2 hyperintense right carotid space lesion measuring 4.8 x 2.4 x 3 cm and a similar lesion measuring 1.7 x 1.6 cm in the left carotid space. Biochemical work-up was positive for elevated 24-hour urine normetanephrines at 2,032 [nl. 131-612 mcg] and plasma normetanephrines at 944 [nl. 0-210 pg/mL]. MIBG scan showed abnormal, bilateral focal uptake within the neck, consistent with carotid space PGLs. Genetic testing was negative. She was started on doxazosin 2 mg and atenolol 25 mg oral daily for symptom control. She lost to follow up since 2021 and re-presented to clinic in 2024 due to recurrence of her symptoms. Repeat MRI showed interval increase in size of the right carotid PGL to 4.1 x 5.1 x 6 cm, the left PGL was stable in size. Plasma normetanephrines were elevated to 1,944 [nl. 0-210 pg/mL] with normal plasma metanephrine of 25.7 [nl. 0-88 pg/mL]. Patient underwent surgical excision of the right sided PGL. Pathology showed a 5.5 cm PGL positive for INSM1, SSTR2A and synaptophysin. On her post-op follow up, she had clinical resolution of her symptoms. Plasma normetanephrines normalized to 68.3 and 49.6 pg/mL at 1 week and 5 weeks post-op respectively. Conclusion: HNPGLs are rarely associated with catecholamine hypersecretion. The prevalence of clinically significant catecholamine secreting HNPGLs has been estimated to be 7.7%-9.2%. However, this patient has bilateral carotid body PGLs with distinct metabolic activity. This case highlights the unpredictable metabolic behavior of these tumors. The low incidence of HNPGLs underscores the importance for clinicians to keep it in the differential diagnosis when patients present with enlarging neck masses associated with symptoms of catecholamine excess or non-specific symptoms. Presentation: Monday, July 14, 2025