paragangliomas of the head and neck

Paragangliomas of the head and neck are rare, representing <0.5% of all head and neck tumors. They arise in a number of locations along the carotid sheath and middle ear including the carotid bifurcation, vagal ganglia, jugular bulb, and tympanic plexus.

For a general discussion of the pathology of these tumors please refer to the paraganglioma article.

Epidemiology

Overall there is a 3:1 female predominance. Two-thirds of cases are diagnosed between the ages of 40 and 60. Approximately 25% are multicentric, and these tend to be familial.

Clinical presentation

Clinical presentation will depend on location.

When involving the middle ear cavity, the tumor may grow large and extend into the external ear: these may present with pulsatile tinnitus, cranial nerve palsies (typically IX-XI, Vernet syndrome), or conductive hearing loss. Direct otoscopic examination may reveal a retrotympanic vascular mass.

In the neck, the patient may present with a local mass.

Pathology

Paragangliomas arise from neural crest cells, which can differentiate into cells of either the parasympathetic or sympathetic nervous system. In the head and neck, paragangliomas tend to be innervated by the parasympathetic system and do not secrete catecholamines and are thus termed nonchromaffin paragangliomas .

Multiple paragangliomas (both sporadic and familial subtypes) are commonly associated with mutations of the succinate dehydrogenase subunit genes .

Associations

Although often sporadically identified in otherwise normal individuals, paragangaliomas are seen associated with a number of systemic conditions including :

Location

They are divided according to location:

Radiographic features

CT
  • useful when bone erosion occurs
  • a moth-eaten pattern is typical
MRI
  • T1: may show a “salt and pepper” appearance; salt representing blood products from hemorrhage (uncommon) and pepper representing flow voids due to high vascularity (common)
  • T1C+ (Gd): demonstrate rapid wash-in and wash-out (as opposed to the more slow and steady enhancement of a schwannoma) 
Angiography
Scintigraphy

Treatment and prognosis

Treatment is usually by excision. Preoperative endovascular embolization is often used to reduce tumor vascularity and aid excision. Radiotherapy may be used for palliation of unresectable lesions.

Malignant transformation is not terribly uncommon and has been reported in 16-19% of glomus vagale tumors, in 6% of carotid body tumors, and in 2-4% of glomus tympanicum tumors.

Differential diagnosis

When completely imaged with CT and contrast-enhanced MRI usually little differential is present. During work-up, however, numerous entities should be considered.

In the middle ear/petrous temporal bone consider:

In the jugular and carotid region consider: