All patients diagnosed with paraganglioma/pheochromocytoma should undergo genetic counseling. It is commonly quoted that 10% of these tumors have a genetic association, however in children less than 18 years old there is an identifiable mutation in 56%. This increases to 70% in children less than 10 years old. The most common associations are von Hippel-Lindau syndrome, MEN 2A and 2B, familial paraganglioma syndromes, and more rarely NF1, tuberous sclerosis, and MEN 1.
- Paragangliomas are rare tumors arising from the sympathetic and parasympathetic paraganglia. 90% occur in the adrenal medulla, in which case they are called a pheochromocytoma. The other 10% are extraadrenal and may occur anywhere from the base of the skull to the pelvis. The organ of Zuckerkandl is the largest extraadrenal collection of chromaffin tissue and extends along the aorta from the level of the renal arteries to just beyond the aortic bifurcation with the highest concentration typically seen at the origin of the inferior mesenteric artery. The majority of these tumors are benign, but 12% will be malignant in the pediatric population. Bilateral tumors are found in 25-34% of patients.
- The vast majority of head and neck paragangliomas are nonfunctional, and generally present with mass effect. Those in the chest and abdomen tend to be functional and present with hypertension, headaches, palpitations, diaphoresis, tremor, and anxiety. Catecholamine excess may result in hypertensive crisis, cardiomyopathy, pancreatitis, stroke, seizures, multiorgan failure, and death. The current diagnostic test of choice is measurement of fractionated plasma and/or urine metanephrines which has a sensitivity approaching 100% for sympathetic chromaffin tumors.
- On ultrasound paraganglioma may appear as solid or mixed solid and cystic masses. Areas of hemorrhage may appear hyperechoic. On CT they appear as enhancing masses which may be heterogeneous due to internal hemorrhage or internal necrosis. Internal calcification is seen in 10-21%. Nonionic contrast does not incite a hypertensive crisis and premedication is not required. On MRI they are classically “light-bulb” bright on T2 weighted images. They are isointense to muscle and hypointense to liver on T1 weighted images, however this may be variable if hemorrhage necrosis is present. Solid components typically demonstrate avid gadolinium enhancement and may demonstrate a “salt and pepper” appearance with enhancing tumor and vascular flow voids. I-123 MIBG is the most common and available functional imaging technique. I-123 is favored over I-131 as it offers better image quality with less radiation dose.
- The treatment of choice is surgical resection. Preoperative biopsy is not indicated, and is potentially dangerous. Medical therapy should be initiated 1-2 weeks before surgery to minimize risk of catecholamine surge during anesthesia induction and manipulation of tumor. In cases of unresecatble malignant disease chemotherapy, radiofrequency ablation, and I-131 MIBG radiotherapy may be considered.
- Statdx, “Pheochromocytoma”, https://my.statdx.com/document/pheochromocytoma/d46d537b-4476-418d-a964-a3d889885667?searchTerm=organ%20of%20zuckerkandl. Accessed 10/24/15.
- Lee et al, Extraadrenal Paragangliomas of the Body: Imagine Features. AJR 2006; 187:492-504
Leung, Stamm, Raja, Low. Pheochromocytoma: The Range of Appearances on Ultrasound, CT, MRI, and Functional Imaging. AJR 2013; 200:370-378
- Saurborn, Kruskal, Stillman, Parangi. Best Cases from the AFIP: Paraganglioma of the Organs of Zuckerkandl. Radiographics 2003;23:1279-1286.
- Waguespack SG et al. A current review of the etiology, diagnosis, and treatment of pediatric pheochromocytoma and paraganglioma. J Clin Endocrinol Metab. 95(5):2023-37, 2010.
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