Cholesteatoma

What it is, and how it forms

Cholesteatoma is a non-cancerous growth of squamous epithelium in the ear. A congenital form is also described.

The way it forms is written out: squamous epithelium forms in small pockets on the tympanic membrane, and the pocket becomes cyst-like as it produces keratin and sloughs over time. There will be middle ear erosion, which creates an environment for anaerobic bacterial growth to occur. That one line explains the rest: the smell comes from the anaerobic growth, the hearing loss from the erosion, and the white mass from the keratin.

It sits among the middle ear causes of conductive hearing loss, together with otosclerosis, trauma such as a ruptured tympanic membrane or a temporal bone fracture, and infection such as otitis media.

Causes and risk

Cholesteatoma is listed as an extracranial complication of acute otitis media, and as a complication of otitis media with effusion alongside hearing loss, chronic mastoiditis, ossicular erosion, and retraction of the tympanic membrane with atelectasis.

It is also a complication of tympanostomy tube (grommet) insertion: focal atrophy of the tympanic membrane at the site of insertion increases the risk of retraction pockets and cholesteatoma. So a history of glue ear treated with grommets is part of what to ask for, even when the grommets fell out by themselves years before.