Paragangliomas of the head and neck

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

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

Epidemiology

Overall there is a 3:1 female predominance, with two. Two-thirds of cases beingare 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 tumour may grow large and extend into the external ear or: 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 lesion may be the presenting complaint. 

Pathology

Paragangliomas arise from neural crest cells. In the head and neck, paragangliomas is that they tend to be innervated by the parasympathetic system and do not secrete catecholamines, and are thus termed nonchromaffin paragangliomas) ¹⁰. 

When multipleMultiple paragangliomas (both sporadic and familial casessubtypes) are commonly associated with mutations of the succinate dehydrogenase subunit genes are common ¹⁰. 

Associations

Although often sporadically identified in otherwise 'normal'normal individuals, paragangaliomas are seen associated with a number of systemic conditions including ¹⁰:

• multiple endocrine neoplasia (MEN)
• neurofibromatosis type 1 (NF1) 
• paraganglioma syndrome
• succinate dehydrogenase mutations
• von Hippel-Lindau syndrome (vHL)

Location

They are divided according to location:

• carotid body tumour (or chemodectoma)
  • located at the carotid body, and splaying the carotid bifurcation
  • most common paraganglioma of the head and neck (60-67% of total)
• glomus tympanicum tumour
  • arise from the glomus tympanicum
  • confined to the middle ear overlying the cochlear promontory
  • arises from the inferior tympanic branch of glossopharyngeal nerve (CN IX) (or Jacobson's nerve)
  • second most common head and neck paraganglioma
• glomus jugulotympanicum tumour
  • arising from the glomus jugulotympanicum
  • extending between the cochlear promontory and jugular foramen
  • arising from Arnold's nerve, the mastoid branch of the vagus nerve (CN X)
• glomus jugulare tumour
  • arising from the glomus jugulare
  • confined to the jugular foramen
  • extending into the middle ear
• glomus vagale tumour
  • arising from the glomus vagale associated with vagus nerve (CN X)
  • least common head and neck paraganglioma

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 haemorrhage (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) ⁹

Angiography

• should demonstrate an intense tumour blush, with
• the most common feeding vessel beingis the ascending pharyngeal artery

Scintigraphy

• will demonstrate high uptake withon ¹¹¹In labelled octreotide ^7-8

Treatment and prognosis

Treatment is usually by excision. Preoperative endovascular embolisation is often used to reduce tumour 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 tumours, in 6% of carotid body tumours, and in 2-4% of glomus tympanicum tumours.

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:

• cholesterol granuloma
• cholesteatoma
• metastasis
• meninigoma
• base of skull tumours

In the jugular and carotid region consider:

• jugular schwannoma
• lymph node metastasis/mass