Paraganglioma

Anu Bansal, MD - Case Coordinator
Karl Edwin Stien, MD - Radiology Discussion
Ron Firestein, MD, PhD - Pathology Discussion
Pablo R Ros, MD, MPH - Attending Radiologist

June 23, 2003

Presentation

Imaging Findings

Axial CT images appear to demonstrate a 4-cm, homogeneous mass centered in the area where one would expect to see the inferior vena cava; it is unclear whether or not the IVC may be compressed behind the mass. Coronal post-contrast MR images through the retroperitoneum show two abnormalities. The mass in the area anterior to the IVC is visible (far left image); the lesion may actually extend into the IVC. In addition, there is another, well-circumscribed mass with a central area of hypointensity. Neither mass appears to be associated with the kidneys.

Differential Diagnosis

Diagnosis

Discussion

The gross specimen is a 6-cm mass removed from the area of the organ of Zuckerkandl. The primarily solid, soft tissue mass is well circumscribed with some hemorrhagic cystic areas. Low-power microscopy shows the mass to be encapsulated and highly cellular. At higher magnification, it is clear that the lesion is comprised of nests of gland-like cells with eosinophilic cytoplasm and round nuclei; the appearance is very similar to the chromatin cells of the adrenal medulla. The cells stain with both synaptophysin and chromogranin; the supportive cells that surround the nests stain with S-100. These findings are consistent with paraganglioma. This particular mass has relatively low mitotic activity (3:50 hpf) and no necrosis, indicating that it is most likely benign.

Radiology Discussion:

Extra-adrenal pheochromocytomas, also known as paragangliomas, glomus tumors, and chemodectomas, are typically malignant tumors arising from neuroectodermal/neural crest tissue. They can occur throughout the body in association with the sympathetic and/or parasympathetic ganglion. The most common locations affected by paragangliomas are the carotid body (so-called ‘carotid body tumor’; the carotid body monitors changes in pH as well as oxygen and carbon dioxide tension, secreting hormones that affect heart rate, respiratory rate, etc.), the jugular bulb (‘glomus jugulari’), middle ear (‘glomus tympanicum’), and the nodose ganglion of the vagus nerve (‘glomus vagale’). Some are functioning endocrine tumors. They are relatively rare, representing 0.03% of all neoplasms, but are the most common tumor of the middle and inner ear. Multiple tumors are present in 5% of cases. There is a female predominance in all locations except the carotid body; the average age of affected patients is 50-60 years (in general, pheochromocytomas are associated with patients in their 20s and 30s and show no preference between genders). Paragangliomas are associated with both von Hippel Lindau disease and multiple endocrine neoplasia II (MENII). In addition, a person’s risk reportedly increases ten-fold with chronic exposure to high altitudes, suggesting a possible correlation with decreased oxygen tension.

The symptoms associated with paragangliomas are varied and depend largely upon the location of the tumor. An enlarging neck mass may be related to carotid body tumor or glomus jugulari. Pulsatile tinnitus and conductive hearing loss are associated with glomus tympanicum. Other symptoms include cranial neuropathies, episodic hypertension, increased heart rate and/or palpitations, and excess production of catacholamines. The tumors often produce mass effect on adjacent structures.

Imaging characteristics are not unique. One feature common among large tumors is a "salt and pepper" appearance on MRI, related to flow voids associated with significant neovascularity. Small tumors do not have this appearance. Signal intensities (isointense on T1 and hyperintense on T2) are nonspecific. Avid early enhancement with contrast can be an important finding, in addition to a "dip" in the dynamic curve at 20-40 seconds post contrast administration. This is distinct from schwannoma and meningioma, which have consistently "hot" perfusion patterns. Bone destruction may be evident on CT images (again, distinct from schwannoma, which typically expands the bone). Angiography will often show a strong capillary blush and is useful for preoperative embolization. Doppler ultrasound will show a nonspecific vascular mass.

References

Yousem DM. Case Review: Head and Neck Imaging. Mosby, St. Louis, 1998:29-30.

Neish AS, Zamani A. Paraganglioma: Case Presentation. BrighamRAD July 1995. http://www.brighamrad.harvard.edu/Cases/bwh/hcache/74/full.html

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