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Cholesteatoma
Key Points
- 1.
Multiple techniques exist for removal of cholesteatomas.
- 2.
Canal wall-up procedures maintain a physiologic ear canal but may have increased risk of residual and recurrent disease.
- 3.
Canal wall-down procedures provide superior visualization of disease during surgery but may require periodic cleaning, difficulty with hearing aids, and water restriction.
- 4.
Ossiculoplasty may be needed to improve hearing if ossicles are damaged.
- 5.
Oto-endoscopy may improve visualization of cholesteatoma in certain areas (e.g., sinus tympani).
Pearls
- 1.
Congenital, primary acquired, and secondary acquired are the different types of cholesteatomas.
- 2.
Cholesteatomas characteristically become infected and/or erode bone, resulting in a variety of complications.
- 3.
CT is the most commonly used imaging modality to evaluate cholesteatomas.
- 4.
Surgery is the definitive treatment, with goals geared toward complete eradication of disease, preservation of hearing, and overall improvement of ear hygiene.
- 5.
Second-stage operations or MRI may be used to evaluate residual and recurrent disease, especially with extensive cholesteatomas after the first operation.
Questions
Pathophysiology, Etiology, and Classification
1
What is a cholesteatoma?
Cholesteatomas are epidermal inclusion cysts of the temporal bone and are composed of squamous epithelium and associated debris. Cholesteatomas enlarge over time and become destructive, commonly with surrounding inflammation and granulation tissue.
The word cholesteatoma was first used to describe its light color and gross resemblance to cholesterol crystals under microscopy. This observation is a misnomer because of the lack of cholesterol or fat in cholesteatomas.
2
What are the different types of cholesteatomas?
The three main types are congenital, primary acquired, and secondary acquired ( Table 43.1 ).
Table 43.1
Various Types of Cholesteatomas and Their Associated Origin
| TYPE | ORIGIN |
|---|---|
| Congenital | Keratinizing epithelium in the middle ear cleft with an intact tympanic membrane; multiple theories exist |
| Primary acquired | Occurs in the setting of tympanic membrane retraction; multiple theories exist |
| Secondary acquired | Occurs in the setting of tympanic membrane perforation; multiple theories exist |
3
Briefly describe the different pathogenic mechanisms.
Congenital cholesteatomas are thought to originate from the keratinizing squamous epithelium of the middle ear. Although the etiology remains unknown, multiple theories exist to describe the origin of the squamous epithelium. These theories include epidermoid cell rests within the middle ear (most favored theory), squamous metaplasia, epithelial migration through tympanic membrane (TM), microperforations, and deposition of desquamated epithelial cells from the amniotic fluid.
Primary acquired cholesteatomas usually arise in the setting of retraction of the TM, usually as a result of otitis media and chronic eustachian tube dysfunction. Although usually arising from the pars flaccida (or epitympanic area), they can also develop in the pars tensa (commonly the mesotympanic area). Alternatively, secondary acquired cholesteatomas arise in the setting of TM perforations. Multiple theories exist to explain the pathogenesis of acquired cholesteatomas, including TM invagination, migration of epithelium through TM perforations, basal cell hyperplasia, squamous metaplasia, and implantation.
4
What is the invagination theory?
Invagination is the most accepted theory of primary acquired cholesteatomas. TM retraction results from negative middle ear pressure due to eustachian tube dysfunction, poor pneumatization of the mastoid, inflammation, and/or TM atrophy. Progressive retraction forms a pocket, resulting in disrupted normal epithelial migration and drainage of keratin debris. As this process progresses, the collection of keratin debris becomes large and a cholesteatoma forms.
5
Why treat cholesteatoma?
Cholesteatomas have a propensity to become recurrently infected and locally destructive. Once infected, eradication of an infection may be very difficult and can result in a variety of intracranial and extracranial complications associated with chronic otitis media. The bacterial flora associated with cholesteatomas are also different from those associated with acute otitis media. Infections associated with cholesteatomas are frequently polymicrobial, with an increase in anaerobes and antibiotic-resistant bacteria.
Local bone destruction can affect various structures in the temporal bone, which can result in hearing loss, vestibular dysfunction, facial nerve injury, and intracranial complications. Bone erosion is thought to be due to an influx of inflammatory mediators due to chronic inflammation and infection.
6
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