Paragangliomas of the head and neck

Paragangliomas of the head and neck are rare tumours, representing <0.5% of all head and neck tumours.

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

Epidemiology

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

When involving themiddle ear cavity, the tumour may grow large and extend into the external ear. Presentation is withpulsatile tinnitus, cranial nerve palsies (typically IX-XI, Vernet syndrome), orconductive hearing loss. Examination may reveal aretrotympanic vascular mass.

Pathology

One particular feature of head and neck paragangliomas is that they tend to be innervated by the parasympathetic system.

Location

They are divided according to location:

• carotid body tumour (or chemodectoma chemodectoma)
  • located at thecarotid body, and splaying thecarotid bifurcation
  • most common paraganglioma of the head and neck (60-67% of total)
• glomus tympanicum tumour
  • arise from theglomus tympanicum
  • confined to themiddle ear overlying thecochlear promontory
  • arises from the inferior tympanic branch ofglossopharyngeal nerve (CN IX) (orJacobson's nerve)
  • second most common head and neck paraganglioma
• glomus jugulotympanicum tumour
  • arising from the glomus jugulotympanicum
  • extending between thecochlear promontory and jugular foramen
  • arising fromArnold's nerve, the mastoid mastoid branch of thevagus nerve (CN X)
• glomus jugulare tumour
  • arising from the glomus jugulare
  • confined to thejugular foramen
  • extending into themiddle ear
• glomus vagale tumour
  • arising from theglomus vagale associated withvagus nerve (CN X)
  • least common head and neck paraganglioma

Radiographic features

CT

• useful when bone erosion occurs
• moth-eaten pattern is typical

MRI

• T1: may show a “salt and pepper” appearance; salt being blood products from haemorrhage (uncommon) and pepper being flow voids due to high vascularity (common)
• C+ (gadolinium): 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 being the ascending pharyngeal artery

Scintigraphy

• will demonstrate high uptake with 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 tumors, and in 2-4% of glomus tympanicum tumours.

Differential diagnosis

In the jugular region consider

• jugular schwannoma