SUN-494 - Pediatric Extra-Adrenal Pelvic Paraganglioma with SDHB Mutation: A Rare Case Presenting Diagnostic and Management Challenges

Background:
Paragangliomas are rare neuroendocrine tumors in children arising from extra-adrenal chromaffin tissue. Pelvic locations are exceedingly uncommon, particularly in adolescents. Mutations in the SDHB gene result in hereditary paraganglioma-pheochromocytoma syndrome, which is associated with a high likelihood of metastatic disease. We report a rare pediatric case of a pelvic paraganglioma with SDHB mutation, emphasizing diagnostic challenges, multidisciplinary management, and implications for hereditary endocrinopathy.

Case Presentation:
A 14-year-old girl presented with a one-year history of episodic hypertension, headaches, diaphoresis, and tachycardia. Initial evaluation included echocardiogram which demonstrated a nonspecific hyperechoic structure on the pulmonic valve. Reassured from a cardiac standpoint, she was discharged with instructions for home blood pressure monitoring. Two weeks later, she returned with headaches, diaphoresis, and dizziness and was found to have a blood pressure of 180/130. She was subsequently admitted for hypertensive crisis. Isradipine, labetalol, and doxazosin were given at that time with symptomatic improvement. Laboratory testing demonstrated an elevated plasma normetanephrine to 30.5 nmol/L. Subsequent MRI revealed a 5.4 cm heterogeneous pelvic mass pressing against the posterior bladder wall, concerning for an extra-adrenal pheochromocytoma. Treatment with surgical excision was pursued. Preoperative blood pressure control was obtained with labetalol and doxazosin. Successful surgical removal was completed, though pathology confirmed positive margins. Postoperatively, the patient experienced resolution of hypertension, headaches, and diaphoresis. Additionally, genetic testing showed a pathogenic SDHB c.725G>A (p.Arg242His) variant, confirming a diagnosis of hereditary paraganglioma-pheochromocytoma syndrome. Follow-up normetanephrine levels decreased significantly to 1.15 nmol/L. While she initially experienced postoperative sciatic pain and sleep disturbances, these symptoms resolved by her outpatient follow-up visit.

Conclusion:
This case underscores diagnostic delays due to subtle and episodic symptomatology, the surgical challenges posed by complex pelvic anatomy resulting in positive margins, and the critical importance of postoperative surveillance. Because SDHB mutations carry a high risk for malignancy, lifelong biochemical and radiographic surveillance is mandatory. This case further highlights the value of multidisciplinary coordination and long-term surveillance in hereditary endocrine syndromes, where both risk of recurrence and quality-of-life outcomes must be carefully managed.

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