Cholesteatoma is a persistent destructive disease of the ear. It is a cystic growth and consists of a skin layer and retained keratin with an inflammatory response and bone resorption on the outside. It can occur in the middle ear, mastoid process and any other part of the temporal bone where skin is not naturally present. Cholesteatoma is not cancerous but can cause a lot of destruction.
The components of a cholesteatoma.
A cholesteatoma consists of a:
1. Matrix (keratinizing squamous epithelium) on the outside
2. Perimatrix (varying thickness of subepithelial connective tissue)
3. Keratin debris on the inside
How common is a cholesteatoma?
It is estimated that cholesteatoma incidence is about 9-12,6 per 100 000 of the adult population per year. It occurs in 3 to 15 cases per 100,000 children. Seen in all races, it occurs slightly more in boys and although it can present at any age usually peaks in the second decade.
The different types of cholesteatoma
Cholesteatoma can be congenital or acquired. Congenital cholesteatoma is less common and is accepted to be present from birth. It occurs due to the failure of the epibranchial placode to involute. Acquired cholesteatoma is more common and develops after birth. Although the exact mechanism of development is still debated, it is usually excepted to develop in response to the tympanic membrane’s pathological alterations. Folding of the tympanic membrane or retraction pocket, often the tympanic membrane is usually the first step that leads to cholesteatoma formation. In some cases the perforation of the tympanic membrane leads to skin ingrowth from the ear canal and the development of cholesteatoma.
The symptoms of cholesteatoma
The most common symptoms are conductive hearing loss with or without a discharging ear. The discharge may have a foul smell. Other less common symptoms include pain, headache, dizziness, vertigo, disequilibrium, facial nerve weakness and tinnitus. In complicated cases, patients may present with serious complications.
Diagnosing a cholesteatoma
A cholesteatoma is diagnosed during a clinical examination of the ear. In cases where debris and ear wax are present, it is essential to note that these should first be cleared to visualize the whole tympanic membrane. Without proper visualization, the cholesteatoma cannot be ruled out. It may have different appearances. If inflammation is present, an aural polyp covering the cholesteatoma may be the only finding. In other cases, perforation of the tympanic membrane with or without discharge and a whitish pearly mass may be seen. One has to be highly careful when only a tiny amount of wax covers part, especially the top part of the tympanic membrane, as this may obscure the cholesteatoma.
Congenital cholesteatoma presents with a white-yellow mass behind an intact tympanic membrane. In cases where it cannot be visulaized but is suspected or where the extent beynd visuslization needs to be assessed imaging with computed tomography (CT)and magnetic resonance imaging (MRI) will be performed.
In order to determine the effect on hearing, the vestibular organ and the facial nerve, hearing tests vestibular tests such as videonystagmography(VNG) and facial nerve conduction studies will be necessary.
The treatment of cholesteatoma
Cholesteatoma needs to be managed; it cannot be left as it will progress, destroying structures in its way. The bones of hearing (ossicles), facial nerve and the inner ear are at risk. Invading the intracranial cavity may lead to meningitis, thrombosis, brain abscesses and even death.
The only definitive treatment is surgical removal. The surgical procedure is called a tympanomastoidectomy. Surgery may be challenging as, on the one side, the cholesteatoma needs to be completely removed, but on the other side, structural damage to intact structures needs to be avoided. If incompletely removed, the cholesteatoma will just persist and grow again (residual cholesteatoma).
It may recur (recurrent cholesteatoma) in up to 15% of cases. This occurs more commonly in children than adults. Therefore meticulous follow up is always important after surgical removal.
Medication is not effective in curing cholesteatoma but is usually described to treat infections or some of the other consequences of the cholesteatoma. Cholesteatoma is not treated with radiation.