The ear: otitis media, cholesteatoma, otosclerosis and ear tumours
- Lesion
Ear disease rarely kills but often impairs hearing: middle ear infection, keratin cysts that erode bone, fused stapes, and a few tumours.
What it is
The commonest ear disorders are acute and chronic otitis media, sometimes leading to cholesteatoma, and otosclerosis. Acute otitis media is a disease of children that starts with a viral infection and becomes bacterial. Chronic infection can perforate the eardrum and spread to the mastoid and brain. Otosclerosis causes conductive deafness by fixing the stapes; tumours include paraganglioma, carcinomas of the external ear and vestibular schwannoma.
Structure
- Acute otitis: hyperemic mucosa, serous then purulent exudate in the middle ear.
- Chronic otitis: granulation tissue, fibrosis, aural polyps, eroded ossicles.
- Cholesteatoma: pearly white mass; stratified keratinising epithelium with lamellated keratin, sometimes cholesterol clefts and giant cell reaction when ruptured.
- Otosclerosis: first fibrous ankylosis, then new spongy, vascular bone replaced by dense bone anchoring the stapes.
Step by step
- A viral upper respiratory infection swells the Eustachian tube, which in children is short and horizontal.
- Negative pressure and trapped fluid in the middle ear are invaded by nasopharyngeal bacteria.
- Repeated or unresolved infection perforates the drum and keeps the middle ear chronically inflamed.
- Squamous epithelium from the drum grows into the middle ear (or the lining undergoes metaplasia) and forms a keratin-filled sac.
- Enzymes and pressure from the expanding cholesteatoma erode ossicles, the mastoid and the tegmen.
- In otosclerosis, disordered bone remodelling (resorption then new bone formation) fixes the stapes.
Common ear lesions
| Lesion | Mechanism | Hearing loss | Risk |
|---|---|---|---|
| Acute otitis media | Bacterial infection after viral URI | Conductive, temporary | Perforation, mastoiditis |
| Chronic otitis media | Persistent infection, perforation | Conductive | Ossicle and bone destruction |
| Cholesteatoma | Keratinising squamous sac | Conductive | Erodes bone; intracranial spread |
| Otosclerosis | Bone fixes the stapes | Conductive, bilateral | Progressive deafness |
Clinical notes
- Otalgia, fever, bulging red eardrum in a child: acute otitis media; pneumococcal vaccination has reduced cases in Colombia.
- Chronic smelly discharge with conductive loss suggests cholesteatoma; it needs surgery.
- Otosclerosis: progressive conductive loss in a young adult with normal eardrum, sometimes worse in pregnancy.
Test yourself
Think of the answer, then tap the question to see it.
What is a cholesteatoma made of?
A cyst lined by keratinising squamous epithelium filled with keratin debris; it is not a neoplasm and contains little cholesterol.
What causes the hearing loss of otosclerosis?
Abnormal bone deposited around the oval window fixes the footplate of the stapes, causing conductive loss.
Which bacteria commonly cause acute otitis media?
Streptococcus pneumoniae, nontypeable Haemophilus influenzae and Moraxella catarrhalis.
Elsewhere in DurgiPedia
- Ear: inner, middle and external ear
- Inner ear: the cochlea and the organ of Corti
- Hearing: middle ear, cochlea and auditory pathway
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Acute Otitis Media (StatPearls (NCBI Bookshelf), 2025); Ear Infections (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.