Cholesteatoma
Definition: Presence of keratinizing squamous epithelium in the middle ear or mastoid. Often described as "Skin in the wrong place".
Why is it a Misnomer?
- Does NOT contain cholesterol crystals.
- Is NOT a tumour (oma).
- Alternative names: Epidermosis or Keratoma.
Structure
Essentially consists of two parts:
1. The Matrix
+
2. Central White Mass
- Matrix: Keratinizing squamous epithelium on thin fibrous stroma.
- Central Mass: Keratin debris produced by the matrix.
Cholesteatoma
Theories of Origin (Genesis)
How does squamous epithelium enter the middle ear cleft?
| Theory | Concept |
|---|---|
| Wittmaack’s | Invagination: Retraction pocket from attic/pars tensa invaginates and forms matrix. |
| Ruedi’s | Basal Cell Hyperplasia: Basal cells of skin proliferate due to infection. |
| Habermann’s | Epithelial Invasion: Epithelium from meatus grows into middle ear through a perforation. |
| Sade’s | Metaplasia: Mucosa transforms into squamous epithelium due to infection. |
| Congenital | Presence of embryonic cell rests. |
Classification
1. Congenital Cholesteatoma
- Origin: Embryonic epidermal cell rests.
- Sites: Middle Ear, Petrous Apex, Cerebellopontine Angle.
- Presentation:
- White mass behind intact TM.
- Conductive hearing loss.
- May rupture spontaneously (mimics CSOM).
2. Primary Acquired Cholesteatoma
Condition: No history of previous otitis media or perforation.
Mechanisms:
- Invagination of Pars Flaccida: Persistent negative attic pressure causes retraction pocket → accumulates keratin.
- Basal Cell Hyperplasia: Induced by subclinical childhood infections.
- Squamous Metaplasia: Of attic epithelium.
3. Secondary Acquired Cholesteatoma
Condition: Pre-existing perforation present (usually posterosuperior marginal or large central).
- Migration: Skin from canal/TM migrates through perforation (common in necrotizing otitis media).
- Metaplasia: due to repeated infections.
Expansion & Bone Destruction
Spread: Follows path of least resistance → Aditus, Antrum, Mastoid, Mesotympanum.
Mechanism of Bone Destruction:
It is Enzymatic (collagenase, acid phosphatase, proteolytic enzymes form osteoclasts).
Note: Old theory of pressure necrosis is no longer accepted.
It is Enzymatic (collagenase, acid phosphatase, proteolytic enzymes form osteoclasts).
Note: Old theory of pressure necrosis is no longer accepted.
Consequences:
- Destruction of ear ossicles.
- Erosion of Bony Labyrinth.
- Erosion of Facial Nerve Canal.
- Erosion of Tegmen Tympani (Intracranial spread).
📚 Source: ENT DHINGRA| Chapter 11
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