eRadiograph Volume 7: Imaging of Oral Cavity | Page 265
Paraganglionoma
Paraganglionomas arise from paraganglionic cells (neuroectodermal origin) which
secrete catecholamines helping the autonomic nervous system respond to physiologic
stresses. These paraganglia are located in the adrenal gland. Extra adrenal location of
paraganglia are in the adventitial layer of blood vessels. In the head and neck region
these occur in four primary locations – at the carotid bifurcation (carotid body), along
the nodose ganglia of the vagus nerve (vagal paraganglioma), in the region of the
jugular bulb (glomus jugulare) and in the middle ear along tympanic plexus respectively
known as (glomus tympanicum)
These tumors are slow growing vascular tumors which are mostly benign – 10% may
be malignant 10% may be multicentric, 10% of paraganglinoma are associated with
MEN 1/2 Syndrome. Lesions may be synchronous or multicentric. Therefore all
potential paraganglioma sites should be screened.
On imaging these appear as densely enhancing soft tissue masses. On MRI they are
hypointense on T1W1, hyperintense on T2W1 with internal flow voids due to
hypervascularity resulting in a salt and pepper appearance.
Carotid Body Paraganglionomas: develop from paraganglia cells in the adventia at
the carotid bifurcation. These cause splaying of the internal and external carotid
arteries. The presence of a lucent halo around the carotid artery indicates the carotid
artery is not involved.
Sympathetic Chain Paraganglionomas
These are very rare tumors arising close to the carotid bifurcation. Since they are
located posterior and medial to the carotid artery they displace the carotid artery
anteriolaterally as compared to vagal paraganglionomas which displace the carotid
artery anteromedially. Unlike vagal Paraganglionomas which do not cause splaying of
the carotid arteries, sympathetic Paraganglionomas may splay the carotid arteries
similar to a carotid body tumor. It is important preoperatively to differentiate a carotid
body tumor from a sympathetic chain Paraganglionomas – because of the functional
and cosmetic impact of Horner Syndrome. If the bulk of tumor is medial to the carotid
bifurcation this would most likely represent a sympathetic chain ganglionoma.
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Carotid Space
Vagal Paraganglionomas: are rare accounting for less than 5% of all head and neck
Paraganglionomas these generally arise high along the extra cranial course of the
vagus nerve close to the skull base thus they may be firmly attached to the skull base as
well as extend intracranially. Vagal paraganglionomas displace the internal carotid
artery anteromedially and do not widen the carotid bifurcation like carotid body
tumors do.