Radiofrequency ablation: a novel approach for treatment of metastatic pheochromocytoma.

About 10%–15% of pheochromocy­ tomas eventually develop metastases (1). Few patients with metastatic pheo­ chromocytoma are suitable candidates for surgical resection of the tumor. This correspondence introduces radiofrequency ablation (RFA) as an alternate treatment modality in pheo­ chromocytoma. RFA is a safe, predict­ able, and effective method for lo­ cal tumor destruction in primary and metastatic carcinomas (2–7). We report on a patient with metastatic pheo­ chromocytoma with a rapidly growing bone metastasis who was treated with RFA. The patient, a 42-year-old man, first presented with episodes of hematuria, hypertension, and palpitations. A 24­ hour urine collection demonstrated el­ evated levels of catecholamines and metanephrines. Computed tomography (CT) scan revealed a 5.5 × 7.5 × 8.0-cm pheochromocytoma invading the poste­ rior urinary bladder wall. His tumor was considered unresectable. The patient was treated with radiotherapy and six cycles of chemotherapy, with 80% tu­ mor shrinkage followed by cystectomy. CT scans 5 years later showed lung metastases and a 0.5-cm third lesion on the right rib. The lesion grew gradually, then rapidly to 3 cm in diameter, with marked elevations in the levels of plasma norepinephrine (6974 pg/mL), free normetanephrine (3516 pg/mL), urinary norepinephrine (707 μg/24 hours), total metanephrines (6090 μg/24 hours), and vanillylmandelic acid (18.2 μg/24 hours). 6-[F]Fluorodopamine positron emission tomography (Fig. 1) and [I]metaiodobenzylguanidine scintigraphy confirmed that the rib lesion was metastatic pheochromocy­ toma. To treat the rib lesion, we chose RFA after we considered the limitations, side effects, and time commitments of radiotherapy, chemotherapy, and sur­ gical resection. Because RFA disrupts cells by heat, marked catecholamine release was anticipated. Therefore, be­ ginning 2 weeks before the proce­ dure, the patient received phenoxyben­ zamine, atenolol, and α-methyl-para­ tyrosine (DemserTM; Merck Sharp & Dohme, West Point, PA). The ad­ equacy of the adrenergic blockade was assessed by a provocative glucagon test 2 days before the RFA. Glucagon in­ creased the patient’s blood pressure, and phenoxybenzamine was increased to 80 mg and DemserTM to 1.5 g once a day. RFA was performed in the interven­ tional CT scan suite after an intercostal nerve block. Probe temperature was gradually increased to 86 °C, with treat­ ment duration progressively increasing from 10 seconds to 10 minutes. RFA resulted in marked norepinephrine release (0.24–2.78 pmol/mL) and hyper­ tension, managed with intravenous labetelol and a nitroprusside infusion. After RFA, phenoxybenzamine and DemserTM were tapered over a 2-week