SAT-068 - Diagnostic Challenges of A Rare Extra-Adrenal Paraganglioma in Von Hippel-Lindau Syndrome

A 69 year old female with Von Hippel-Lindau syndrome, complicated by renal cell carcinoma and hemangioblastomas, presented with right-sided hearing loss and pulsatile tinnitus. Imaging revealed an erosive mass at the right jugular bulb. Although radiologic interpretation favored paraganglioma, otorhinolaryngology assessment favored a diagnosis of endolymphatic sac tumor based on clinical judgment and Von Hippel-Lindau history. Due to a preoperative episode of hypertensive urgency, her surgical resection was aborted. She was referred to endocrinology due to history of labile hypertension refractory to medical therapy, raising suspicion for pheochromocytoma. Her biochemical workup revealed borderline elevations in plasma normetanephrine (1.2 nmol/L with reference upper limit 0.9) and urinary norepinephrine (6961 pmol/L with reference upper limit 4800), which were discordant with her clinical severity. Abdominal imaging was negative for adrenal masses. DOTATATE PET/CT revealed abnormal avidity at the jugular bulb, and a secondary avid nodule in the pancreatic uncinate process, and a diagnosis of Glomus Jugulare paraganglioma was made. She was treated with aggressive alpha blockade with doxazosin and phenoxybenzamine and underwent Gamma Knife Radiotherapy, leading to initial symptom relief and successful weaning of alpha blockers. She had a recurrence of labile hypertension shortly after her procedure, but catecholamines and chromogranin A remained negative, raising concerns for an active pancreatic neuroendocrine tumor or paraganglioma. She is currently pending endoscopic ultrasound with biopsy to guide further management.

Paragangliomas are rare neuroendocrine tumors arising from the autonomic nervous system. Although Von Hippel-Lindau syndrome is traditionally associated with pheochromocytoma, extra-adrenal manifestations can occur. Head and neck paraganglioma typically originate from the parasympathetic chain and are predominantly non-secretory. Contrastingly, pancreatic paraganglioma typically arise from the sympathetic chain and may exhibit secretory function. A multidisciplinary approach and lifelong surveillance are prudent in these patients for early diagnosis of syndrome associated complications. This case highlights the diagnostic complexities of paragangliomas in hereditary syndromes when biochemical findings are equivocal despite strong clinical suspicion. Functional imaging with DOTATATE was pivotal in establishing diagnosis and guiding management. Although surgical resection remains standard of care, stereotactic radiosurgery may be an alternative in selected patients, with care taken to maintain aggressive alpha blockade to prevent perioperative catecholamine overload.

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