[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Head and neck](https://durgical.com/en/general-pathology/areas/head-neck/) › The ear: otitis media, cholesteatoma, otosclerosis and ear tumours

# 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.

Updated Nov 12, 2026

## Key points

- Acute otitis media: pneumococcus, nontypeable H. influenzae, Moraxella catarrhalis after a viral infection; Eustachian tube dysfunction.
- Chronic otitis media: P. aeruginosa, S. aureus, fungi; perforation, ossicle destruction, mastoiditis, brain abscess.
- Necrotising (malignant) otitis externa: P. aeruginosa in elderly diabetics; spreads to skull base.
- Cholesteatoma: cyst lined by keratinising squamous epithelium full of keratin debris; erodes ossicles and bone; not a neoplasm, not cholesterol.
- Otosclerosis: abnormal bone around the oval window fixes the stapes footplate; conductive hearing loss, usually both ears, often familial (autosomal dominant, variable penetrance).
- Tumours: middle ear paraganglioma (glomus tympanicum), basal and squamous carcinoma of the auricle, vestibular schwannoma of the internal canal.

## 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](https://durgical.com/en/conditions/acute-otitis-media/) | Bacterial infection after viral URI | Conductive, temporary | Perforation, mastoiditis |
| [Chronic otitis media](https://durgical.com/en/conditions/otitis-media-with-effusion-and-chronic-suppurative-otitis-media/) | Persistent infection, perforation | Conductive | Ossicle and bone destruction |
| [Cholesteatoma](https://durgical.com/en/conditions/cholesteatoma/) | Keratinising squamous sac | Conductive | Erodes bone; intracranial spread |
| [Otosclerosis](https://durgical.com/en/conditions/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.

## Memory aid

Cholesteatoma has no cholesterol and is no tumour: it is skin in the wrong place.

## 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.

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## Elsewhere in DurgiPedia

- [Ear: inner, middle and external ear](https://durgical.com/en/embryology/ear-inner-middle-and-external-ear/)
- [Inner ear: the cochlea and the organ of Corti](https://durgical.com/en/histology/inner-ear-the-cochlea-and-the-organ-of-corti/)
- [Hearing: middle ear, cochlea and auditory pathway](https://durgical.com/en/physiology/hearing-middle-ear-cochlea-and-auditory-pathway/)

## Connections

## Related 3

- [Rhinitis, sinusitis, pharyngitis and tonsillitis](https://durgical.com/en/general-pathology/rhinitis-sinusitis-pharyngitis-and-tonsillitis/)
- [Neck cysts and paraganglioma](https://durgical.com/en/general-pathology/neck-cysts-and-paraganglioma/)
- [Community-acquired pneumonia: organisms](https://durgical.com/en/general-pathology/community-acquired-pneumonia-organisms/)

## Related conditions 7

- [Acute otitis media](https://durgical.com/en/conditions/acute-otitis-media/)
- [Otitis media with effusion and chronic suppurative otitis media](https://durgical.com/en/conditions/otitis-media-with-effusion-and-chronic-suppurative-otitis-media/)
- [Cholesteatoma](https://durgical.com/en/conditions/cholesteatoma/)
- [Otosclerosis](https://durgical.com/en/conditions/otosclerosis/)
- [Otitis externa](https://durgical.com/en/conditions/otitis-externa/)
- [Necrotising (malignant) otitis externa](https://durgical.com/en/conditions/necrotising-otitis-externa/)
- [Vestibular schwannoma (acoustic neuroma)](https://durgical.com/en/conditions/vestibular-schwannoma/)

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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](https://www.ncbi.nlm.nih.gov/books/NBK470332/) (StatPearls (NCBI Bookshelf), 2025); [Ear Infections](https://medlineplus.gov/earinfections.html) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/the-ear-otitis-media-cholesteatoma-otosclerosis-and-ear-tumours/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/the-ear-otitis-media-cholesteatoma-otosclerosis-and-ear-tumours/