Cholesteatoma

What is a cholesteatoma?

A cholesteatoma is an abnormal growth of skin inside the ear, specifically in the middle ear space, which is located behind the eardrum. Under normal circumstances, the outer ear is lined with skin that slowly grows outward and sheds naturally. In a cholesteatoma, this process goes wrong. Instead of shedding outward, skin cells become trapped in a pocket on the eardrum (or pass through a perforation in the eardrum), where they continue to accumulate. These pockets usually form because the ear is not ventilated properly, creating negative pressure that pulls the eardrum inward. 

Over time, this accumulation of skin cells forms a sac or cyst filled with layers of dead skin. This sac slowly enlarges and becomes chronically infected. Importantly, a cholesteatoma is not a tumor and not cancer, but it behaves aggressively because it can erode bone and damage critical structures of the ear as it accumulates dead skin and grows larger: as the cholesteatoma grows, it can destroy the delicate hearing bones, invade the mastoid bone behind the ear, and in advanced cases reach structures involved in balance, facial movement, and even the brain.

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How does a cholesteatoma form? (Pathophysiology)

The development of a cholesteatoma is generally tied to abnormal pressure regulation in the middle ear. The middle ear is normally ventilated by the Eustachian tube, which connects the ear to the back of the nose. When this tube does not function well, negative pressure builds up inside the ear. To learn more about the Eustachian tube, read this article. 

There are a few theories that are used to explain how cholestestomas form:

Retraction pocket theory (most common)

This is the most widely accepted explanation. Chronic negative pressure in the ear, due to Eustachian tube dysfunction, pulls part of the eardrum inward, especially the upper portion because it is thinner and weaker (this part is called the pars flaccida). Over time, this inward fold deepens and forms a retraction pocket. Skin normally moves outward along the eardrum and the ear canal, but within this pocket, skin becomes trapped and cannot shed properly. Dead skin accumulates, bacteria thrive, and a cholesteatoma slowly forms.

Migration through a perforation

If the eardrum has a long-standing perforation, skin from the ear canal can grow inward through the hole into the middle ear. Once inside, the skin continues to grow and shed, leading to cholesteatoma formation.

Implantation theory

Skin cells may be accidentally implanted into the middle ear during ear surgery or trauma, such as a significant injury to the eardrum. These implanted cells can later develop into a cholesteatoma.

Congenital cholesteatoma

In rare cases, a cholesteatoma is present from birth. This happens when skin cells become trapped in the middle ear during development of the fetus. These patients often have no history of ear infections, and the eardrum appears intact. Congenital cholesteatomas are most often diagnosed in childhood.

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Who typically develops a cholesteatoma? (Risk factors)

Cholesteatomas can affect both children and adults, but they are particularly common in people with long-standing middle ear problems.

Children with recurrent ear infections, chronic fluid behind the eardrum, or poor Eustachian tube function are at higher risk. Adults who had ear disease as children may develop cholesteatomas later in life. 

Certain anatomical or medical conditions increase risk, including cleft palate, chronic nasal congestion, severe allergies, and sinus disease. These conditions interfere with proper middle ear ventilation.

People with a history of chronic eardrum perforations, prior ear surgeries, or poorly ventilated mastoid bones are also more vulnerable. Smoking in adults contributes to chronic inflammation and worsens Eustachian tube function, indirectly increasing risk.

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How do cholesteatomas present? (Clinical presentation)

One of the most concerning aspects of cholesteatoma is how quietly it can progress.

The most common symptom is chronic ear drainage that may be foul-smelling and tends to return despite treatment. Unlike a simple ear infection, the drainage often improves temporarily with drops but never fully resolves. Learn more about the types of ear drainage in this article.

Hearing loss is very common and usually develops slowly. Most patients experience conductive hearing loss, meaning sound is not efficiently transmitted through the damaged middle ear structures. You can learn more about the types of hearing loss here.

Some patients notice a sense of ear fullness or pressure. Pain is not always present and, when it is, often signals infection or complications. Read this article to learn more about ear fullness.

As the disease advances (which usually takes many years), patients may develop dizziness, permanent hearing loss, or facial weakness, which occurs when the cholesteatoma erodes the facial nerve canal. These symptoms require urgent evaluation. Discover the different types of vertigo here.

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Clinical evaluation and diagnostic work-up

Medical history

The evaluation begins with a detailed history, focusing on recurrent or persistent ear infections, chronic drainage, previous ear surgeries, hearing changes, dizziness, facial symptoms, and childhood ear disease. Long-standing symptoms are particularly important clues.

Physical examination

A careful ear examination using a microscope is essential. The physician looks closely at the eardrum for:

• Retraction pockets, especially in the upper part of the eardrum (just like in the picture shown at the beginning of this article)

• White debris or keratin (dead skin) behind the eardrum or in a pocket

• Eardrum perforations

• Signs of chronic inflammation or bone erosion

The ear canal, mastoid area, facial nerve function, and balance are also assessed. The Eustachian tubes are also examined with a camera.

Hearing evaluation (audiogram)

An audiogram provides a baseline hearing assessment. Most patients show conductive hearing loss, but mixed or inner ear hearing loss may be present in advanced disease or with complications. Read this article to learn more a about audiograms.

Imaging studies

A CT scan of the temporal bone is commonly used to assess the extent of bone erosion and mastoid involvement. It helps surgeons plan the operation but cannot reliably distinguish cholesteatoma from scar tissue or inflammation.

An MRI with diffusion-weighted imaging (DWI) is especially useful in selected cases, such as when the diagnosis is uncertain or when monitoring for residual or recurrent disease after surgery.

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Potential complications of cholesteatoma

When a cholesteatoma grows, it can destroy nearby structures and lead to serious complications. The complications listed below usually develop over several years, not over a few months or weeks, so there is generally ample time to seek medical care before they occur.

Erosion of the middle ear bones (ossicles)

This is the first and most common complication. It results in hearing loss. Fortunately, erosion of the ossicles can usually be corrected during surgery, and hearing can often be largely restored.

Erosion of the inner ear

If the cholesteatoma continues to grow, it may erode the bone of the inner ear. The most common site is the horizontal semicircular canal, which is one of the organs of balance. Erosion in this area can cause dizziness or chronic vertigo. More rarely, and when the cholesteatoma becomes very large, it can erode the cochlea (the organ of hearing), leading to permanent and irreversible hearing loss.

Facial paralysis

If the cyst continues to grow toward the facial nerve, which runs through the middle ear, patients may develop facial weakness or paralysis, affecting eye closure and facial expression. This presentation is also rare and is a sign of a very advanced cholesteatoma. Surgery can relieve pressure on the nerve and sometimes restore facial function, but the damage is often permanent in cases of long-standing paralysis.

Dangerous infections

In advanced or infected cases, bacteria can spread beyond the ear, leading to mastoiditis, meningitis, a brain abscess, or venous sinus thrombosis. These are rare but potentially life-threatening complications.

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Treatment options

Surgical treatment: tympanomastoidectomy with ossicular chain reconstruction

Surgery is the definitive treatment for cholesteatoma. In other words, there are no medications that can cure it.

The surgery is called a tympanomastoidectomy. The goal is to completely remove the cholestestoma, clean the ear, reconstruct the eardrum and fix the hearing, all of this with the ultimate goal of creating a safe, dry ear.

If the hearing bones are damaged, an ossicular chain reconstruction (or ossiculoplasty) may be performed to restore sound transmission. You can learn more about ossiculoplasty in this article. This may be done during the same surgery (most commonly) or at a later stage.

The priority is always disease control and patient safety, with hearing improvement as a secondary goal.

Conservative management in selected patients

In older patients or those with significant medical conditions, surgery may carry excessive risk. In carefully selected cases with limited disease, regular microscopic cleaning (debridement) in the office may help control symptoms.

It is important to understand that this approach does not eliminate the cholesteatoma and requires strict, lifelong follow-up.

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Risk of recurrence and long-term follow-up

Cholesteatoma has a known tendency to recur, particularly in patients with ongoing Eustachian tube dysfunction. After a tympanomastoidectomy, it is estimated that the risk of recurrence is about 5%.

Long-term follow-up is essential and typically includes regular ear examinations, repeat audiograms, and MRI with diffusion-weighted imaging (MRI DWI) to detect recurrence early.

Follow-up often continues for many years, as recurrence can occur even after an initially successful surgery.