A 35-year-old woman has episodic hypertension, palpitations, and diaphoresis. 24-hour urine shows elevated metanephrines (normetanephrine 2.8× upper limit). MRI adrenal shows a 3 cm right adrenal mass. Genetic testing reveals a succinate dehydrogenase subunit B (SDHB) mutation. Which feature of her tumor most mandates closer long-term surveillance?
- A High malignant potential with metastatic disease ✓
- B Bilateral pheochromocytoma risk
- C Associated primary hyperparathyroidism
- D Risk of cerebellar hemangioblastoma
Correct answer: A. High malignant potential with metastatic disease
Explanation
SDHB mutations (SDH = succinate dehydrogenase) are associated with hereditary pheochromocytoma/paraganglioma syndrome type 4. SDHB-mutated tumors carry the highest risk of malignancy among all pheochromocytoma genetic subtypes — approximately 30–40% develop metastatic disease. This contrasts with VHL (cerebellar hemangioblastomas), MEN2 (bilateral pheochromocytomas, hyperparathyroidism), and NF1 mutations. Lifelong surveillance with biochemical and imaging follow-up is essential given the malignant potential.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.