Cholesteatoma

What is a cholesteatoma?

A cholesteatoma is rare. The truthful answer to what causes it, is 'we don't really know'. Skin cells from the lining of the ear canal seem to get trapped in the middle ear (which doesn't normally contain skin cells).

Skin cells, including those that line the ear canal, normally multiply regularly to replace those that have died. Usually these skin cells just flake off.

The dead cells are trapped too and build up. This build-up of dead skin cells over time is what forms the cholesteatoma.

What type of problem is a cholesteatoma?

Cholesteatoma is an uncommon condition where a cyst-like growth develops in the ear. It can be a birth defect (congenital problem) but usually occurs as a complication of long-standing (chronic) changes to the pressure in the ear. The most common symptoms are loss of hearing and a foul-smelling discharge from the ear.

Cholesteatoma

Can a cholesteatoma be cancerous?

It is not a cancerous (malignant) condition but is important because it can lead to serious complications such as permanent deafness, damage to nearby nerves and life-threatening illnesses such as meningitis.

What are the symptoms of a cholesteatoma?

An early cholesteatoma may have no symptoms. The first symptom is usually a discharge from one ear. It is usually slightly watery, sometimes with a green or yellow colour. The discharge might be slightly smelly and this often looks to a doctor like an external ear infection (otitis externa) or an infection of the inner ear (otitis media) with a perforated eardrum.

Because it looks just like these common infections, it is usually treated (wrongly) with antibiotic ear drops or pills and although it might get slightly better with these treatments, it will never fully clear up. A cholesteatoma is not painful.

After a while you may get hearing problems in that ear, if the cholesteatoma is left untreated it can spread into the balance centres of the inner ear, causing dizziness. Ringing in the ear (tinnitus) can also occur. Eventually, in very rare cases, it can spread right next to the brain and cause an infection in the brain tissue or the lining of the brain. This is very unlikely to happen these days in the western world.

How fast does a cholesteatoma grow?

Symptoms start very gradually, over several months.

How do we hear?

The ear is divided into three parts - the external ear, the middle ear and the inner ear. The middle ear, which is behind the eardrum (the tympanic membrane) is filled with air. Air comes from the back of the nose up a thin channel called the Eustachian tube. In the middle ear there are three tiny bones (ossicles) - the hammer (malleus), anvil (incus) and stirrup (stapes). The inner ear includes the cochlea and semicircular canals.

Sound waves come into the external ear and hit the eardrum. The sound waves cause the eardrum to vibrate. The sound vibrations pass from the eardrum to the ossicles. The ossicles then transmit the vibrations to the cochlea in the inner ear. The cochlea converts the vibrations to sound signals which are sent down a facial nerve from the ear to the brain, allowing us to hear.

The semicircular canals in the inner ear contain a fluid that moves around as we move into different positions. The movement of the fluid is sensed by tiny hairs in the semicircular canals which send messages to the brain down the ear nerve to help maintain balance and posture.

Detail of middle ear

What causes a cholesteatoma?

The cause of a cholesteatoma is quite difficult to explain, and even now is not fully understood.

We all have skin inside our ear canal. It is meant to be there and is a normal part of our ear. But with a cholesteatoma the skin right next to the eardrum, deep in the ear, gets sucked in gradually to where it shouldn't be. No one quite knows why this happens but it is usually related to the eardrum being very retracted (drawn inwards, deeper than it is meant to be).

This skin then forms a tiny pearl, or ball, that keeps burrowing its way deeper into the ear over many months. It damages the delicate bones inside the middle ear - the bit that is responsible for hearing. At this point it becomes painful.

Is a cholesteatoma serious?

If left untreated it will push further and further inside the ear causing permanent hearing loss, through the inner ear and possibly even next to the brain. In the western world it would be very unusual for it to get that bad but this can happen in the developing world.

There are two types of cholesteatoma

• Congenital cholesteatoma: is a problem that in theory happens from birth. For some reason, even though the eardrum is normal, tiny skin cells get sucked into the middle ear, blocking the Eustachian tube. This then causes long-term fluid in the middle ear (which is usually free of fluid) and can cause hearing loss. This becomes apparent between the ages of 6 months to 5 years when the child's hearing doesn't develop properly. This is a very rare condition and the cause isn't fully known.
• Acquired cholesteatoma: develops later, usually in adults between 30 and 50 years old. Again, the cause isn't fully known. Sometimes a cholesteatoma in an adult can happen from having a grommet - a tiny tube that is put through the eardrum as a treatment for middle ear problems - as a child.

How common is a cholesteatoma?

Around 7-13 people per 100,000 of the population will be diagnosed with a cholesteatoma each year, and it is estimated that an average GP will see around one new case every 4-5 years.

What are the risk factors for cholesteatoma?

Cholesteatoma is more common in men than in women and is usually seen in people who have a history of ear infections. Other risk factors include previous surgery or trauma to the ear, certain genetic problems such as Turner syndrome or Down's syndrome, and occasionally a strong family history of the condition.

How is a cholesteatoma diagnosed?

The GP or ear specialist (ENT doctor) may suspect a cholesteatoma based on the typical symptoms. When the ear is examined with a torch (an otoscope), the cholesteatoma may be seen. Often there is a hole (perforation) in the eardrum (the tympanic membrane) too.

Because the symptoms come on slowly and mimic common ear infections, the diagnosis is often delayed.

• It is very difficult for a GP to see a cholesteatoma because usually it causes a lot of pus in the ear which blocks the view to the eardrum.
• For this reason the diagnosis is made by an ear specialist at a hospital.
• The ear specialist will use a tiny suction tube to suck away the discharge and look at the eardrum in detail with a microscope that magnifies the view.
• By looking in detail, close up, at the eardrum, a specialist can see the cholesteatoma pushing through the eardrum.
• To then see how far it has spread inside the ear, a specialist scan is needed: this is usually a CT scan or an MRI scan.

What does a cholesteatoma look like?

In the close-up image below, the mass of white keratin debris seen on the left-hand side is a cholesteatoma.

Cholesteatoma

By Michael Hawke MD (Own work), CC BY 4.0, via Wikimedia Commons

Do I need any further tests?

Hearing tests (audiometry) may show deafness or hearing loss and are usually performed in a hospital clinic. Samples (swabs) of the ear discharge may also be taken. The discharge often contains a germ (bacterium) called Pseudomonas which is responsible for the smell. A CT scan might be needed to see the extent of the damage caused by the cholesteatoma, and to plan further treatment.

How to treat a cholesteatoma

A cholesteatoma does not have a blood supply so taking antibiotics by mouth will not work at all because the antibiotics can't get into it. Antibiotic ear drops can clear away any infection around the cholesteatoma but will not treat the actual problem. Many people will have had antibiotic ear drops prescribed to them without success, before they are diagnosed with a cholesteatoma.

The treatment is done by an ear, nose, and throat specialist (an ENT doctor) and usually consists of an operation under a general anaesthetic. The aim of the surgery is removing the cholesteatoma and then to clear out part of the middle ear so air can circulate around better. This will hopefully stop the cholesteatoma coming back.

There are different types of cholesteatoma surgery that can be done and a specialist ear doctor will advise you which operation is best. The most common is called a 'combined approach tympanoplasty' where the damaged part of the eardrum is removed and the bone at the back of the ear, the mastoid, is cleared out.

If the patient is not fit for surgery (for example, if they are very old or frail or have other serious medical conditions) then regular visits to an ear specialist will be recommended. This is so the specialist can suction out any tiny bits of wax or debris deep in the ear that can contribute to a cholesteatoma. This will not solve the problem but can keep it from getting worse.

What are the possible complications and why is treating it important?

Untreated, a cholesteatoma will slowly grow and expand. As it grows it can eat into (erode) and destroy anything in its path.

Possible complications that may develop over time include:

• Damage and eventual destruction of the tiny bones of the ear (the ossicles). If these are damaged, permanent deafness can occur.
• Damage to the mastoid bone. This is the thick bony lump you can feel behind the ear. The mastoid bone is normally filled with pockets of air (a bit like a honeycomb). A cholesteatoma can grow into the mastoid bone, causing infection and destroying it.
• Damage to the cochlea and other structures in the inner ear. This can cause permanent deafness on that side, and/or dizziness and balance problems.
• Damage to nearby nerves travelling to the face. This can cause weakness (paralysis) of some of the facial muscles.
• Cholesteatoma is often infected and this infection can spread to nearby body parts. In rare cases a cholesteatoma can erode through the skull next to the ear and into the brain. As a result of spreading infection, conditions such as meningitis and brain abscess can develop. These conditions can cause death.

Is any follow-up required for a cholesteatoma ?

If you have had a cholesteatoma, you will need to be followed up in an ENT clinic.

Can a cholesteatoma come back?

You will also need to have your ears cleaned regularly at the clinic to remove wax and any dirt that has accumulated. The specialist will need to ensure that the cholesteatoma has not returned.

If the ear starts discharging again, further surgery may be required. MRI scans are increasingly being used to replace the need for further check-up surgery.

What is the outlook?

This depends on how much damage has been caused by the cholesteatoma by the time it is found and treated. It is also affected by whether any complications such as meningitis or deafness have occurred. The earlier surgery is done, and attending for regular follow-up, the better the chance of a good outcome.