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CHOLESTEATOMA — Comprehensive Clinical Review

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1. DEFINITION

It is not a true neoplasm — it is a destructive, expansile epidermal cyst capable of eroding bone through osteoclast activation.

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2. ETIOLOGY — TABLE

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3. PATHOLOGY — CHART FORM

3A. Structural Components

CHOLESTEATOMA
├── MATRIX (inner lining)
│     └── Hyperproliferative keratinizing squamous epithelium
│         (basal layer shows increased mitotic activity)
│
├── PERIMATRIX (surrounding connective tissue)
│     └── Fibrous stroma with:
│         • Macrophages, lymphocytes, plasma cells
│         • Osteoclast precursor cells
│         • Fibroblasts, histiocytes
│         • RANKL-expressing stromal & T-cells
│
└── CONTENTS
      └── Laminated keratin debris (desquamated squames)
          + Small amounts of cholesterol crystals
          + Occasional anaerobic bacteria (if infected)

3B. Bone Erosion Mechanism — Pathophysiology Flowchart

Keratinizing squamous epithelium in confined middle ear space
                    ↓
     Keratin accumulation → expansion → infection
                    ↓
     Keratin extrudes into perimatrix subepithelium
                    ↓
         Inflammatory cascade activated
                    ↓
     RANKL ↑ on stromal cells & activated T-lymphocytes
     + M-CSF upregulation
                    ↓
     Osteoclastogenesis via RANK–RANKL–OPG axis
                    ↓
  Multinucleated osteoclasts recruited to bone surface
                    ↓
     Enzymatic bone resorption:
       • Acid phosphatase
       • Collagenase
       • Cathepsin-like proteases (pH ~4.0 microenvironment)
                    ↓
     PROGRESSIVE BONE DESTRUCTION (intermittent)
       → Ossicular erosion (most common: long process of incus)
       → Scutum erosion (attic wall)
       → Tegmen erosion → intracranial extension
       → Labyrinthine fistula (horizontal SCC — 7–10% of cases)
       → Facial canal dehiscence
       → Petrous apex involvement

Old theory (abandoned): Pressure necrosis — disproven because measured cholesteatoma pressure (1.3–11.9 mmHg) never exceeds capillary perfusion pressure (~25 mmHg). Osteoclastic resorption is the established mechanism.

3C. Histopathology

• Stratified squamous epithelium with surface keratinization
• Subepithelial chronic inflammatory infiltrate
• Osteoclasts at bone interface with resorption lacunae (Howship's lacunae)
• Endochondral otic capsule bone is relatively resistant to erosion compared to intramembranous bone of middle ear and mastoid

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4. CLINICAL FEATURES

Symptoms

Signs on Otoscopy / Microscopy

Complications

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5. INVESTIGATIONS

Audiological

Imaging

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6. MANAGEMENT

A. Non-Pharmacological (Conservative)

Conservative management is temporizing only — cholesteatoma can only be cured by surgery.

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B. Pharmacological

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C. Surgical Treatment

1. Complete eradication of cholesteatoma (primary)
2. Management of complications
3. Hearing reconstruction (secondary)

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SURGERY 1: CANAL WALL-UP (CWU) TYMPANOMASTOIDECTOMY (Intact Canal Wall / Closed Technique)

1. Patient supine, head turned contralateral, arm abducted; post-aural skin incision 1 cm behind auriculocephalic sulcus
2. Elevation of periosteum; identify spine of Henle (landmark for antrum) and linea temporalis
3. Cortical mastoidectomy: systematic exenteration of mastoid air cells with continuous irrigation; identify mastoid antrum, horizontal (lateral) semicircular canal, fossa incudis, short process of incus, sigmoid sinus, tegmen
4. Antrotomy: open antrum widely
5. Atticotomy: remove lateral attic wall (scutum) bone to expose cholesteatoma in epitympanum
6. Careful matrix dissection: methodical removal of cholesteatoma preserving ossicular chain if possible; trace posteriorly through antrum into mastoid
7. Facial recess approach (posterior tympanotomy): thin posterior canal wall and drill facial recess (between facial nerve and chorda tympani) to expose sinus tympani, hypotympanum, round window
8. Ossicular assessment: evaluate continuity; remove matrix from ossicular surfaces; preserve stapes superstructure
9. Ossicular chain reconstruction (if needed): PORP (partial ossicular replacement prosthesis) or TORP (total), incus interposition, or stage for later reconstruction
10. Tympanoplasty: temporalis fascia underlay graft to reconstruct TM; gelfoam packing in middle ear
11. Canal packing: ribbon gauze or BIPP packing; skin closure with absorbable sutures; head bandage

• Oral antibiotics (5–7 days); analgesia; antiemetics
• Canal packing removed at 2–3 weeks in clinic
• Audiogram at 6–8 weeks
• Second-look surgery at 12 months to detect residual disease (or DWI-MRI as non-invasive alternative)
• Regular follow-up every 6 months

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SURGERY 2: CANAL WALL-DOWN (CWD) — MODIFIED RADICAL MASTOIDECTOMY (MRM) / RADICAL MASTOIDECTOMY (Open Cavity / Exteriorization)

• Radical mastoidectomy: posterior canal wall removed + middle ear mucosa stripped + TM removed; middle ear obliterated; Eustachian tube plugged; no hearing reconstruction — reserved for extreme disease
• MRM (standard): posterior canal wall taken down, middle ear mucosa preserved where possible, TM remnant preserved, hearing reconstruction attempted

• HRCT temporal bone (essential for surgical planning)
• PTA + tympanometry; speech audiometry
• Informed consent: mastoid cavity requiring lifelong cleaning, water precautions, possible permanent hearing loss, facial nerve risk, cavity problems (chronic discharge, recurrent infection)
• Treat active infection preoperatively
• NPO 6–8 hrs; anaesthetic assessment; mark operative side; hair shaving; IV antibiotics at induction

1. Post-aural incision; periosteal elevation; identify landmarks (spine of Henle, linea temporalis, Macewen's triangle)
2. Cortical mastoidectomy: complete air cell exenteration including tip cells, Trautmann's triangle (retrolabyrinthine cells); identify facial nerve, lateral SCC, sigmoid sinus, tegmen
3. Lowering of the facial ridge: the posterior bony canal wall is drilled down flush with the level of the facial nerve — the key distinguishing step of canal-wall-down surgery; this externalizes the middle ear and mastoid into a single cavity
4. Meatoplasty: conchal cartilage and/or skin removed to enlarge the external meatus adequately for cavity drainage, inspection, and cleaning; pinna sutured forward if necessary
5. Removal of all cholesteatoma matrix from middle ear, epitympanum, mastoid
6. Saucerization: all bony overhangs and ledges smoothed to create a self-cleansing, bowl-shaped cavity without recesses where keratin can re-accumulate
7. Tympanoplasty (in MRM): temporalis fascia or perichondrium to reconstruct TM remnant; middle ear reconstructed if ET function adequate
8. In radical mastoidectomy: middle ear obliterated; ET orifice plugged with muscle/fascia
9. Cavity lined with a split-thickness skin graft or allowed to epithelialize spontaneously
10. BIPP or ribbon gauze packing; wound closure; mastoid dressing

• IV/oral antibiotics; analgesia
• Pack removal and first cavity inspection at 2–3 weeks
• Cavity cleaning under microscope at 6 weeks, then every 3 months for life
• Water precautions — ear plug always when bathing/swimming
• Audiogram at 6–8 weeks; hearing aid if required
• No second-look surgery needed — cavity is directly visible on clinic examination
• Watch for cavity problems: persistent discharge, polyps, recurrent infection

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SURGERY 3: ENDOSCOPIC EAR SURGERY (EES) — Modern Adjunct

• Limited attic cholesteatoma (primary acquired, early congenital)
• Superior visualization of sinus tympani, hypotympanum, anterior epitympanum
• Avoids post-aural incision; can be combined with mastoidectomy (combined approach)

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Surgical Decision Summary Table

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Quick Clinical Summary