Paragangliomas are neoplasms arising from the paraganglia(1,2) usually seen in the head and neck,
chest and abdomen; commonly seen in specific locations: middle ear,
jugular foramen,
carotid body,
aorto-pulmonary region,
posterior mediastinum and Zuckerkandl's body.
Paragangliomas arising in the head and neck are quite rare and represent less than 1 % of all paragangliomas.
Clinical presentation:
The lesions in the middle ear cavity usually present with symptoms such as:
Pulsatile tinnitus
Conductive hearing loss
Cranial nerve palsies
The lesions in the neck usually present as a local enlarging mass.
Associations:
Multiple systemic conditions may be associated with paragangliomas such as(3).
- Multiple endocrine neoplasia (MEN)
- Neurofibromatosis type 1
- Paraganglioma syndrome
- Succinate dehydrogenase mutations
- Von Hippel-Lindau syndrome(VHL)
The head and neck paragangliomas are divided based on their location into:
Carotid body tumour: Most common paraganglioma,
it arises from the carotid body and splays the carotid bifurcation.
Glomus jugulare: Limited to the jugular foramen,
may extend to the middle ear.
These paragangliomas arise from the paraganglion cells distributed along the Jacobson’s nerve or Arnold’s nerve.
Glomus tympanicum: Limited to the middle ear cavity and lies over the cochlear promontory.
Arises from the paraganglion cells distributed along the Jacobson's nerve.
Glomus vagale: Least common paraganglioma.
Most commonly arises from the ganglion nodosum of the vagus nerve.
Imaging features:
CT and MRI are the primary imaging modalities for diagnosing paragangliomas along with functional imaging with metaiodobenzylguanidine(MIBG) scintigraphy.
Angiography is usually used for planning preoperative embolization(4).
CT: On CECT,
the glomus tumours show enhancement with associated bony erosions in most of the cases; whereas carotid body tumours appear as avidly enhancing lesions causing splaying of the carotid bifurcation.
MRI: A characteristic salt and pepper appearance is seen on T1 weighted images with intense enhancement on T1 post contrast images(5).
The lesions appear hyperintense on T2 and FLAIR images.
Angiography: The lesions show intense tumour blush.
Scintigraphy: Most of the lesions show high uptake on 111In labelled octreotide.
Treatment:
Excision is the mainstay of treatment.
Preoperative embolization - to reduce the tumor size.
Radiotherapy - recommended in unresectable cases.