Cholesteatoma

Definition & Pathogenesis - The Skin Invasion

• Definition: Destructive, expansile lesion of keratinizing squamous epithelium (skin) in middle ear, mastoid, or temporal bone.
• Types:
  • Congenital: Embryonic epidermal rests; pearly white mass behind intact TM.

    ⭐ Congenital cholesteatoma typically presents as a white mass behind an intact tympanic membrane in a child with no history of otorrhea or perforations.

  • Acquired (Common):
    • Primary: TM retraction (pars flaccida) from chronic Eustachian tube dysfunction (ETD).
    • Secondary: Epithelial migration through pre-existing TM perforation.
• Key Pathogenesis Theories (Acquired):
  • Invagination (Wittmaack): ETD → Negative pressure → Retraction pocket → Keratin accumulation.
  • Epithelial Migration (Ruedi): Basal cell migration through TM defect.
  • Metaplasia (Habermann): Chronic inflammation transforms mucosa (less favored).

Clinical Features - The Silent Destroyer

• Symptoms (often insidious):
  • Persistent, foul-smelling, scanty ear discharge (otorrhea).

    ⭐ Foul-smelling, scanty, persistent ear discharge is highly characteristic of cholesteatoma.

  • Progressive conductive hearing loss (CHL); may become sensorineural (SNHL).
  • Dull earache (otalgia); severe pain suggests complications.
  • Vertigo, tinnitus (labyrinthine involvement).
  • Facial weakness (late, ominous sign).
• Signs (Otoscopy):
  • Attic or posterosuperior marginal perforation or deep retraction pocket.
  • 
  • Visible whitish/pearly keratin debris or flakes.
  • Ossicular chain erosion, granulation tissue, or aural polyp.
  • Positive fistula test (e.g., Hennebert's sign) if labyrinthine erosion.

Investigations - Spotting the Culprit

• Otoscopy: Key initial exam. Reveals attic or posterosuperior pars tensa retraction pocket, keratin debris, granulations, or polyp.
• Tuning Fork Tests (Rinne, Weber): Suggest conductive hearing loss (CHL).
• Pure Tone Audiometry (PTA): Quantifies CHL; may show mixed loss if cochlea involved.
• Microscopy: Detailed examination, allows for suction clearance.
• CT Scan (HRCT Temporal Bone):
  • Assesses bony erosion (scutum, ossicles, tegmen, sigmoid plate).
  • Shows extent of soft tissue mass.

  ⭐ HRCT temporal bone is the gold standard imaging for assessing bony erosion and extent of cholesteatoma.

• MRI (DW-MRI): Differentiates cholesteatoma from granulation tissue or cholesterol granuloma, especially in post-operative recurrence. Useful if CT is equivocal.

Complications - Danger Zones

• Intracranial (↑ mortality):
  • Meningitis: Most common intracranial.
  • Brain abscess: Temporal lobe, cerebellum.
  • Lateral sinus thrombophlebitis.
  • Otitic hydrocephalus (pseudotumor cerebri).
• Extracranial:
  • Facial nerve palsy.
  • Labyrinthitis (serous/suppurative) → SNHL, vertigo.
  • Mastoiditis & subperiosteal abscess (e.g., Bezold's, Citelli's).
  • Petrositis (Gradenigo's syndrome: VI nerve palsy, retro-orbital pain, otorrhea).
• Key Spread Pathways (Danger Zones):
  • Tegmen tympani/mastoideum → Middle cranial fossa.
  • Sinodural angle (Trautmann's triangle) → Posterior fossa, sigmoid sinus.
  • Medial wall (oval/round windows) → Inner ear.
  • Fallopian canal dehiscence → Facial nerve.

⭐ Facial nerve palsy is the most common cranial nerve palsy associated with cholesteatoma.

Management - Surgical Showdown

⭐ The primary goal of cholesteatoma surgery is to create a safe, dry, and disease-free ear; hearing preservation/reconstruction is secondary.

• Surgical Goals: Complete disease eradication, create a permanently safe, dry, aerated ear. Hearing preservation/reconstruction is secondary.
• Main Approaches:

-   **Canal Wall Up (CWU):** e.g., Atticotomy, Intact Canal Wall Mastoidectomy. Preserves posterior canal wall.
-   **Canal Wall Down (CWD):** e.g., Modified Radical Mastoidectomy (MRM). Removes posterior canal wall, exteriorizes disease.

• Ossiculoplasty: Reconstructs ossicular chain if eroded; can be staged.

High-Yield Points - ⚡ Biggest Takeaways

• Cholesteatoma is keratinizing squamous epithelium in the middle ear/mastoid.
• Acquired type commonly arises from pars flaccida retraction (Attic).
• Key symptoms: painless, foul-smelling otorrhea; progressive conductive hearing loss.
• CT temporal bone is crucial for diagnosis and delineating extent.
• Mainstay of treatment is surgical eradication (e.g., mastoidectomy).
• Serious complications include ossicular erosion, facial palsy, and intracranial spread.
• Congenital type: pearly white mass behind intact TM, often in anterosuperior quadrant_._