What is a glomus tumour of the ear?
A glomus tumour of the ear is a paraganglioma: a slow-growing, usually benign neuroendocrine tumour of neural crest–derived paraganglia. Most head and neck paragangliomas arise from parasympathetic paraganglia. They are also called chemodectomas. Their defining property is marked hypervascularity, which explains the pulsatile tinnitus, the red colour behind the eardrum and the risk of heavy bleeding at surgery.
Temporal bone paragangliomas are the second most common head and neck paragangliomas after the carotid body tumour, forming about 20–30% of the group. StatPearls gives a rough split of head and neck paragangliomas: carotid body 44–48%, glomus jugulare 16–24%, glomus tympanicum about 20% and glomus vagale about 8%. There is a clear female predominance, and the average age at presentation is the fifth decade.
Two tumours share the temporal bone. Glomus tympanicum (tympanomastoid paraganglioma) arises from the tympanic branch of the glossopharyngeal nerve (Jacobson's nerve) or the auricular branch of the vagus (Arnold's nerve) on the promontory. Glomus jugulare (tympanojugular paraganglioma) arises from paraganglia in the adventitia of the dome of the jugular bulb. Glomus tympanicum is described as the most common tumour of the middle ear.
How do glomus tympanicum and glomus jugulare differ?
| Feature | Glomus tympanicum | Glomus jugulare |
|---|---|---|
| Origin | Jacobson's or Arnold's nerve on the promontory | Paraganglia in the adventitia of the jugular bulb dome |
| Jugular bulb | Not involved | Involved and eroded |
| Otoscopy | Small red mass behind an intact drum; margins may be fully visible (Indian texts teach the rising sun sign here) | Red mass rising from the floor of the middle ear (StatPearls describes the rising sun appearance here) |
| CT temporal bone | Soft-tissue mass on the promontory | Moth-eaten erosion of the jugular foramen; Phelps sign |
| Cranial nerves | Rarely affected | IX–XII may be involved as the tumour grows |
| Fisch class | A (and B if hypotympanum and mastoid are involved) | C or D |
| Usual surgery | Transcanal or endoscopic for small tumours | Infratemporal fossa approach type A for classes C and D |
The distinction is anatomical and drives everything else. A tympanicum tumour can extend into the mesotympanum, hypotympanum, mastoid, Eustachian tube and external canal, but without involving the jugular bulb. A jugulare tumour spreads through the hypotympanic air cells, around the jugular bulb, inferior petrosal sinus and carotid artery into the jugular foramen and posterior cranial fossa.
Because the jugular foramen transmits the glossopharyngeal, vagus and accessory nerves, with the hypoglossal canal close by, a large jugulare tumour can cause hoarseness, dysphagia, shoulder weakness and tongue deviation. StatPearls reports lower cranial nerve deficits in up to 10% at presentation. Facial palsy is uncommon in the natural course and suggests deeper invasion.
What are the symptoms and the classic otoscopic signs?
The commonest complaints are pulsatile tinnitus and hearing loss. In a 2025 multicentre glomus tympanicum series, 89.1% had pulsatile tinnitus and 56.5% had conductive hearing loss. Hearing loss may be conductive, sensorineural or mixed, but conductive loss is more common because the mass fills the middle ear and damps the ossicles. Some patients have bloody otorrhoea, aural fullness, vertigo or otalgia.
On otoscopy the classic finding is a red or purple, pulsatile mass behind an intact tympanic membrane. When the mass is based on the floor of the middle ear with prominent vessels, it looks like a sun rising over the horizon: the rising sun sign. Indian ENT textbooks classically link the rising sun sign to glomus tympanicum, while StatPearls describes it with jugulare — in an MCQ, tympanicum is the expected answer. If the tumour erodes through the drum, it appears as a bleeding polyp in the canal. Pneumatic otoscopy raises the pressure and makes the mass blanch: this is Brown's sign.
| Sign | Where it is seen | Meaning |
|---|---|---|
| Rising sun sign | Otoscopy | Red mass rising from the floor of the middle ear behind the drum |
| Brown's sign | Pneumatic otoscopy | Mass blanches when pressure in the canal is raised |
| Phelps sign | CT temporal bone | Erosion of the caroticojugular crest (spine) by a jugular foramen tumour |
| Salt-and-pepper appearance | MRI | Flow voids (pepper) with haemorrhage or slow flow (salt) in a hypervascular mass |
| Moth-eaten bone | CT temporal bone | Irregular erosion of the jugular foramen and skull base |
About 1–3% of glomus tumours secrete catecholamines (reviews quote up to 8% for all temporal bone paragangliomas). A functional tumour can cause labile hypertension, palpitations, headache, sweating, tremor and flushing, mimicking a phaeochromocytoma. Such symptoms must be checked before any embolisation or surgery, because handling the tumour can release catecholamines.
Which investigations confirm a glomus tumour?
High-resolution CT of the temporal bone shows bone involvement. Tumour-related destruction appears as irregular, moth-eaten erosion. The key CT discriminator is the caroticojugular crest (spine), the bony ridge between the carotid canal and the jugular foramen: its erosion by a jugular foramen tumour is the Phelps sign. Contrast-enhanced CT can detect tumours smaller than 1 cm.
Contrast-enhanced MRI is the preferred initial imaging for suspected glomus jugulare. It shows an avidly enhancing lesion extending from the jugular bulb into the middle ear and delineates posterior fossa, neck and multicentric disease. The salt-and-pepper appearance is most obvious in tumours larger than 1 cm: the pepper is flow voids from large vessels and the salt is haemorrhage or slow flow.
- Angiography: shows the tumour blush and feeders; the ascending pharyngeal artery (a branch of the external carotid) is the main feeding vessel, with contributions from the occipital artery.
- Balloon test occlusion: checks whether the patient would tolerate sacrifice of the internal carotid artery.
- Biochemistry: 24-hour urinary catecholamines and metanephrines, or plasma metanephrines, for a suspected functional tumour.
- Audiometry: pure-tone and speech audiometry as a baseline.
- Genetics: testing for SDHx gene mutations is part of the work-up, because a substantial minority of head and neck paragangliomas are hereditary.
What does a paraganglioma look like under the microscope?
The tumour is made of round cells grouped into alveolus-like nests or balls of 5 to 30 cells, called zellballen. Nuclear pleomorphism is common but mitoses are rare, so atypia does not mean malignancy. Dense fibrous or myxoid stroma separates the nests, and thin-walled, sinusoidal capillaries run throughout, which is the histological basis for the tumour's vascularity.
Only 1–5% of glomus jugulare tumours are malignant. There are no reliable histological criteria for malignancy: it is diagnosed only when metastases appear in sites where paraganglia do not normally occur. About 80% of paragangliomas are sporadic. Hereditary forms present earlier and can be bilateral or functional. Multicentric tumours (for example with a carotid body or vagal paraganglioma) account for 10–20% of head and neck paragangliomas.
How are glomus tumours staged by Fisch and Glasscock-Jackson?
The Fisch classification and the Glasscock-Jackson classification are the two most widely used systems. Fisch covers both tumours in one scale, based on location and extent; the modified Fisch–Mattox version (Sanna) subdivides classes A and B. Glasscock-Jackson grades tympanicum and jugulare tumours separately, each from I to IV.
| Class | Extent |
|---|---|
| A | Glomus tympanicum: limited to the mesotympanum (A1 margins visible on otoscopy; A2 margins not visible) |
| B | Glomus hypotympanicum: hypotympanum, mesotympanum and mastoid, without erosion of the jugular bulb |
| C1 | Destroys the jugular bulb and foramen; no carotid invasion |
| C2 | Invades the vertical carotid canal |
| C3 | Invades along the horizontal carotid canal |
| C4 | Reaches the foramen lacerum and cavernous sinus along the carotid |
| D | Intracranial extension: De extradural, Di intradural (1 = up to 2 cm, 2 = more than 2 cm) |
| Grade | Glomus tympanicum | Glomus jugulare |
|---|---|---|
| I | Small mass limited to the promontory | Small tumour involving jugular bulb, middle ear and mastoid |
| II | Completely fills the middle ear | Extends under the internal auditory canal; may extend intracranially |
| III | Fills middle ear and extends into the mastoid | Extends into the petrous apex; may extend intracranially |
| IV | Fills middle ear and mastoid or extends through the drum into the canal; may extend anterior to the carotid | Extends beyond the petrous apex into the clivus or infratemporal fossa; may extend intracranially |
How is a glomus tumour treated?
There is no single algorithm; treatment is individualised to age, tumour extent, cranial nerve function and fitness. Observation with serial contrast MRI is reasonable for selected patients: StatPearls reports that about 65% of glomus jugulare tumours stay stable or regress, and about 40% grow slowly, averaging 0.9 mm per year.
- Small tympanicum tumours (Fisch A1, A2, B1): transcanal microscopic or endoscopic excision; larger ones need a postauricular approach.
- Fisch C and D tumours: most often removed through the infratemporal fossa approach type A with extensions as needed.
- Preoperative embolisation: recommended for Fisch C and D tumours considered for surgery, usually 24 to 72 hours before operation, to cut blood loss and operating time.
- Embolisation alone: rarely obliterates the tumour because of revascularisation; it is essentially palliative.
- Radiotherapy: external-beam radiotherapy or stereotactic radiosurgery for elderly or unfit patients, bilateral tumours, residual disease after subtotal resection, or as primary treatment; pooled analyses report about 92% tumour control with radiosurgery.
- Functional tumour: alpha-blockade (for example phenoxybenzamine started about two weeks before surgery) first, and a beta-blocker only after alpha-blockade.
Surgery for jugulare tumours carries real cranial nerve morbidity. StatPearls notes that complete resection is achievable in about 80% of cases, but new postoperative deficits of nerves IX to XII occur in up to 60%. This is why subtotal resection followed by radiosurgery for the residue has gained favour. Recurrence after treatment is under 10% overall but higher in familial disease, so long-term follow-up is needed.
Which glomus tumour traps recur in exams?
- Pulsatile tinnitus plus a red mass behind an intact drum: think paraganglioma first, not otitis media with effusion.
- Brown's sign is blanching on pneumatic otoscopy; the rising sun sign is the otoscopic appearance of a mass rising from the middle-ear floor.
- Phelps sign is a CT sign (erosion of the caroticojugular crest), not an otoscopic one.
- Hearing loss is usually conductive, although sensorineural or mixed loss also occurs.
- The main feeder is the ascending pharyngeal artery.
- Fisch C means the jugular bulb is destroyed; D means intracranial extension.
- Malignancy is defined by metastasis, not by histological atypia.
Compare the middle-ear differentials. A high-riding or dehiscent jugular bulb and an aberrant internal carotid artery are vascular differentials listed by StatPearls, which is one reason imaging precedes any surgical exploration. StatPearls also lists cholesteatoma, lower cranial nerve schwannoma, meningioma and endolymphatic sac tumour among the differentials. See chronic suppurative otitis media and otosclerosis for the other conductive-loss stems.