Glomus Tumor - Types, Clinical Features, Diagnosis

Glomus tumor is a tumor originating from the para-ganglionic cells. Para ganglionic cells are the cells of the sympathetic nervous system and are responsible for auto-regulation. The para-ganglionic cells are also known as glomus bodies. One very important feature of the para ganglionic cells or the glomus bodies is that they secrete catecholamines, namely epinephrine, nor-epinephrine, and dopamine. Glomus is a benign tumor but is a locally invasive tumor. 

These glomus bodies or the para ganglionic cells are seen in the major blood vessels, near the aortic arch, near the common carotid, internal and external carotid, and the internal jugular vein, because these blood vessels carry major blood supply to our body and chemoreceptor are needed in such areas to sense if there is an elevation, decrease in the pressure, decreased oxygenation, increased carbon dioxide, and to maintain internal homeostasis.

The chemoreceptor in this case will be the glomus bodies. These glomus bodies are found around major blood vessels. If something inappropriate is happening these will immediately compensate for it. The Glomus tumor is the most benign tumor of the middle ear. The glomus bodies are the para -ganglionic cells of the sympathetic nervous system. They are present around major blood vessels like the aortic arch, and jugular vein, and are responsible for auto regulation. Glomus tumors originating from the para ganglionic cells are called paragangliomas. Glomus is one such paraganglioma which secrete catecholamines. Because the glomus tumors secrete catecholamines there will be a sympathetic excess. The two types of glomus tumors are:

i. Glomus Tympanicum

ii. Glomus Jugulare

Read this blog further to get a quick overview of this important topic for ENT preparation and ace your NEET PG exam preparation.

Microscopic examination of glomus tumor

Benign and slow growing Thin walled blood sinusoids with no contractile muscle – hence excessive bleeding; extremely vascular No capsule and hence locally invasive Microscopically, glomus tumors have loose blood sinusoids. The blood vessels in this tumor typically lack the tunica media layer or the smooth muscle layer. This will cause the blood vessels to not be able to contract. Therefore, from these areas, one can present with profuse bleeding. When there is a glomus tumor in the scenario, one must think of profuse bleeding as a clinical manifestation. So, there is a lack of tunica media. These tumors have no capsules causing the tumor to be able to spread locally to the adjacent sides. The arrangement of cells present in the tumor, microscopically when seen, resembles a pattern. This pattern is called the Zell Ballen pattern. 

Important Pointers

• Can be associated with Von Recklinghausen neurofibromatosis, Sturge weber syndrome, tuberous sclerosis and Von Hippel Lindau
• RULE OF 10
• 10% of them are familial. This means that there is a genetic history and through the family, the tumor can be happening 10%. 
• 10% of them secrete catecholamines.
• 10% are multicentric. It means it can happen on multiple site.

This means that it is not a rule that every glomus tumor will secrete catecholamines. Only 10% of such tumors secrete catecholamines. Multicentric means that it can happen on multiple sites. Glomus tumors can be associated with Von Recklinggausen neurofibromatosis, Sturge Weber syndrome, tuberous sclerosis, and Von Hippel Lindau disease. (clinical MCQs)

Types of Glomus

• Glomus tympanicum – arises from promontory
• Glomus jugulare – arises from the dome of the jugular bulb

Spread of glomus tumor

• Inferiorly – jugular foramen
• Anteriorly – ET to nasopharynx 
• Posteriorly mastoid 
• Superiorly into brain

Glomus is a locally invasive lesion due to the lack of capsules. The roof of the middle ear is formed by the tegmen tympanum which separates the middle ear from the middle cranial fossa. If the tumor goes superiorly it can enter the middle cranial fossa. 

• If the tumor goes inferiorly, it will go towards the jugular foramen and be the internal jugular vein. The anterior wall of the middle ear contains an opening to the eustachian tube, and if the tumor goes anteriorly it will go towards the eustachian tube. Posteriorly, the tumor can go toward the mastoid air cells. The spread of the tumor depends on its location.
• Laterally, the tumor can spread to the tympanic membrane and present as a bleeding polyp of the external auditory canal. 
• Medially, the tumor will go into the petrous pyramid. When a tumor spreads, it can have associated clinical features. If it goes into the temporal lobe of the brain, there can be localizing features of a temporal lobe lesion like aphasia, hemiplegia, and hemianopia, these features present are indications of cranial spread. 
• When there is a jugular involvement, the 9th, 10th, and 11th cranial nerves could also be involved. If the tumor spreads to the inner ear the patient can have vertigo. To understand the clinical scenario it is important to know that a tumor in the middle ear can spread to the surroundings. 

Clinical Features

Intratympanic tumor

• Bleeding
• Gradually progressive hearing loss
• Tinnitus
• Otoscopy: Red reflex through intact tympanic membrane
• Rising sun appearance: When tumor arises from floor of middle ear 
• Pulsation sign / Brown sign: When pressure in the ear canal increases the tumor pulsates vigorously.

Bleeding - Because it is an extremely vascular tumor and the blood vessels like the smooth muscle layer, when it starts to bleed, it will bleed profusely. 

Gradually Progressive Conductive Hearing Loss - Loss of conduction of sound from the external ear into the middle ear happens gradually over time along with the growth of the tumor.

Pulsatile Tinnitus - Typically the tumor comes from the sympathetic plexus that surrounds the blood vessels. When blood flows from these major blood vessels, transmitted pulsations go to the tumor which can be heard by the patient. The patient will complain of hearing sounds in the year that resembles the heartbeat, in such a case. There is pulsatile tinnitus. When one is complaining of pulsatile tinnitus, the glomus tumor must be ruled out. Pulsatile tinnitus is always suggestive of a glomus tumor.

Rising Sun Appearance - If there is a mass in the middle ear, it can either be a glomus tympanicum or it can be a glomus jugulare. But when one sees from the external auditory canal, red bulging can be seen in the tympanic membrane in the case of glomus tympanicum. In patience with glomus jugulare, a red reflex is present on the floor of the middle ear that represents a Rising Sun. This appearance is a very important sign in patients with glomus tumors. The slide to the left shows a red reflex on the floor of the middle ear suggestive of glomus jugulare. When there is a tumor originating from the promontory, it looks like the slide on the right where the tympanic membrane is red and bulging.

The Brown Sign - There is a glomus jugulare tumor in the middle ear. If a Seigel's Pneumatic Speculum is put in the external auditory canal, and the cuff is inflated, the pressure in the middle ear will increase. This will cause the tumor to vibrate vigorously and become pale, turning to a pink-brown. However, it will again become red. This pink-brown color is known as the brown sign.

Acquinos Sign - These tumors typically get their blood supply from branches of the ICA (ascending pharyngeal artery). Near the hyoid bone, the common carotid bifurcates into internal and external. If the ICA is compressed by applying pressure on the neck and then waiting for some time, the blood supply to the ascending pharyngeal artery is reduced, and therefore the blood supply to the tumor will  get cut off. The red tumor will start becoming pale as can be seen through an otoscopic examination.

Clinical features based on the spread

• Laterally – Red fleshy bleeding polyp
• Medially – Dizziness, facial palsy 

Clinical Features 

• Intracranial spread causes cranial nerve palsy: Late feature 
• 9th to 12th nerves are involved
• Eustachian tube block 
• When a tumor is going laterally into the external auditory canal it will present as a bleeding polyp of the external auditory canal.
• When a tumor grows medially it will cause dizziness and facial palsy. 
• If the tumor grows superiorly and can spread intracranial, it will cause cranial nerve palsy. 
• If the tumor grows inferiorly, it can involve the 9th, 10th, and 11th nerves. If it goes anteriorly, the Eustachian tube gets blocked. Intracranial spread is a late feature and the jugular foramen is involved whenever there is the involvement of the floor.

Symptoms due to excess Catecholamines

Glomus tumor is a paraganglioma and secretes catecholamines (adrenaline, noradrenaline, and dopamine) in 10% of the patients (rule of 10) causing sympathetic excess. Such a patient can present with:

• Headache 
• Sweating 
• Palpitation 
• Hypertension 
• Anxiety

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Diagnosis of glomus tumor:

• CT scan with contrast is the IOC
• MRI
• Angiography 
• Serum levels of catecholamines and their byproducts like vanillylmandelic acid and metanephrines 

CECT

• When there is a patient who is presenting with all of the above-discussed symptoms showing that there is a probability of it being a glomus tumor, the investigation of choice would be a CT scan. The middle ear is surrounded by bones, except for the thin tympanic membrane. Since this is locally invasive, the erosion of the bones will be understood on a CT scan. 

MRI

• It is an extremely vascular condition, the vascularity of the tumor hence needs to be understood. A contrast CT Scan (CECT) is carried out to understand the intravenous vascularity of the tumor. One can also access the erosion of the bones. 
• In some individuals, there might be a cranial spread. If the tegmen is eroded or the jugular is involved, one can opt for an MRI to assess the intracranial spread of the disease. 

Angiography

• Angiography – is done to identify the feeding vessel and embolize it. The feeder is ascending pharyngeal artery 
• Serum levels of catecholamines and their byproducts like  vanillylmandelic acid and metanephrines

Treatment of Choice:

Embolization followed by Surgical excision 

• Radiation for inoperable tumors 
• The feeding vessel to the tumor needs to be identified which is possible through angiography. The most common blood supply to the tumor is through the Ascending pharyngeal artery.  The tumor has a major blood vessel that is giving its branches and this blood vessel is identified through angiography. 
• Embolization is also carried out through angiography. Embolization is when the feeding blood vessel to the tumor is identified and blocked. This will cause that tumor to become avascular and one can now operate on the tumor through surgical excision.
• Once the blood vessel is blocked after embolization, the tumor will stop getting its nutrition and become avascular. About 24 to 48 hours later, an operation is done to remove the tumor. 
• If there is a patient at home then surgery cannot be done because there is an extensive cranial spread or neck spread or if the tumor is not receiving the supply from one artery but from multiple arteries, or when it is getting direct supply from the carotid, radiation is done for such inoperable tumors.
• Serum levels of catecholamines and their byproducts like vanillylmandelic acid and metanephrines are also checked because during surgery sympathetic excess is unwanted. It can lead to fatal complications such as uncontrolled hypertension.

Radiological Signs

Phelps Sign

 In the CECT, a very typical sign is seen which is the Phelps sign. It is a radiological sign. As can be seen in the slide there is the ICA bulge on both sides. 

The sigmoid sinus then identifies which lies in the posterior border of the mastoid; it continues towards the internal jugular vein. A dense bone is present between the jugular and the mastoid called the carotico-jugular spine. 

On the disease's side, this bone is absent. Some soft tissue is present there, which is the glomus tumor that eroded the bone. The erosion of the carotico-jugular spine bone is called the Phelps sign.

MRI showing Salt and Pepper appearance

The MRI of a patient suffering from a glomus tumor will have areas that are white and areas that are grey (due to the microhemorrhages that happen within the tumor). White and grey dots can be seen in the slide above. This appearance is called the Salt and Pepper appearance.

Fisch Classification

• The classification and the type give one an idea of the spread of the tumor and the according approach to surgery will be decided.

A-Tumors restricted to middle ear (glomus tympanicum tumor)

B-Tumors restricted to tympanomastoid site 

C-Tumors involving the infra-labyrinth portion towards the petrous apex

D1-Tumor with intracranial invasion (<2cm)

D2-Tumor with intracranial invasion (>2cm)

• When the tumor is localized only to the middle ear, it is called a Fisch type A tumor. 
• When the tumor is localized from the middle ear to the mastoid, it is called a Fisch type B tumor. 
• If the tumor is going from the middle ear to the mastoid, to the apex of the petrous bone, it is a type C.
• When there is a cranial spread, it is a type D.

Frequently Asked Questions:

Q: Where does the Glomus Tumor originate from?

Answer: Glomus tumor is a tumor originating from the para-ganglionic cells.

Q: What is the investigation of choice for Glomus Tumor?

Answer: Contrast Enhanced CT

Q: What is the Phelps sign?

Answer: The erosion of the carotid-jugular spine bone is called the Phelps sign.

Q: Does the Glomus Tumor bleed?

Answer:  Yes, a glomus tumor bleeds a lot because it is an extremely vascular tumor, and there are a lot of blood vessels in the smooth muscle layer, which, when it starts to bleed, will bleed profusely.

This is everything that you need to know about Glomus tumor  for your ENT preparation. For more interesting and informative blog posts like this download the PrepLadder App and keep reading our blog!