Paraganglioma

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Diagnosis Definition

Paragangliomas (also called “glomus tumors”) are rare neuroendocrine neoplasms arising from paraganglionic cells of neural crest origin; most occur in the abdomen and only 3% occur in the head and neck; 2-13% are malignant, 1-3% are hormonally active, and age of onset is most commonly the 4th and 5th decades
The most common head and neck paraganglioma is the carotid body tumor, which occurs at the carotid bifurcation and typically presents as a painless, slowly growing lateral neck mass
Other common locations in the head and neck are the jugular foramen (“glomus jugulare”), the middle ear (“glomus tympanicum”), and along the vagus nerve (“glomus vagale”); the term glomus jugulotympanicum is used when the tumor involves both the middle ear cavity and the jugular foramen

Imaging Findings

Paragangliomas are circumscribed, polypoid, hypervascular masses with intense homogeneous enhancement on MRI; early enhancement on dynamic imaging helps distinguish them from meningiomas and schwannomas
Vascular flow voids can be seen as hypointense foci within the tumor giving it a “salt-and-pepper” appearance
Splaying of the internal and external carotid arteries is a common feature of a carotid body tumor; as the tumor enlarges, it encases but does not narrow the caliber of the vessels
Glomus vagale tumors can compress and displace the internal jugular vein posterolaterally and displace the internal carotid artery anteromedially; there is no widening of the carotid bifurcation

Pearls

In contrast to schwannomas and meningiomas, paragangliomas involving the jugular foramen tend to demonstrate a “moth-eaten” or infiltrative pattern of bony erosion
About 75% of paragangliomas are sporadic; the remaining 25% are hereditary (and have an increased likelihood of being multiple and developing at an earlier age)
Familial tumors are commonly associated with multiple endocrine neoplasia (MEN IIA and IIB) and neuroectodermal syndromes (tuberous sclerosis, neurofibromatosis, and von Hippel-Lindau disease)

References

Rao AB, Koeller KK, Adair CF. From the archives of the AFIP. Paragangliomas of the head and neck: radiologic-pathologic correlation. Armed Forces Institute of Pathology. RadioGraphics 1999; 19(6):1605-1632
Lee KY, Oh YW, Noh HJ, Lee YJ. Extra-adrenal paragangliomas of the body: imaging features. American Journal of Roentgenology 2006; 187:492-504

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