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CHOLESTEATOMA — Comprehensive Clinical Review

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1. DEFINITION

Key: Cholesteatoma 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 / FLOWCHART

3A. Structural Components

CHOLESTEATOMA
├── MATRIX (innermost layer)
│     └── Keratinizing squamous epithelium (hyperproliferative basal layer)
├── PERIMATRIX
│     └── Subepithelial fibrous connective tissue + inflammatory cells
│         (macrophages, lymphocytes, osteoclast precursors)
└── CONTENTS
      └── Laminated keratin debris (desquamated squames)

3B. Bone Erosion Mechanism (Pathophysiology Flowchart)

Squamous epithelium in confined space
        ↓
Accumulation of keratin debris → pressure + infection
        ↓
Keratin extrudes into perimatrix
        ↓
Inflammatory cascade activated
        ↓
RANKL ↑ on stromal cells & activated T-cells
        ↓
Osteoclastogenesis (RANK–RANKL pathway)
        ↓
Multinucleated osteoclasts recruited to bone surface
        ↓
Enzymatic bone resorption:
  • Acid phosphatase
  • Collagenase
  • Cathepsin-like proteases (pH ~4.0 microenvironment)
  • M-CSF upregulation
        ↓
BONE DESTRUCTION (intermittent, progressive)
  → Ossicular erosion (most common: long process of incus)
  → Scutum erosion
  → Tegmen erosion → intracranial extension
  → Labyrinthine fistula (horizontal SCC, 7–10% of cases)
  → Facial canal dehiscence

Note: Pressure necrosis theory (old) has been abandoned — 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 active keratinization
• Subepithelial fibrous tissue with chronic inflammatory infiltrate
• Osteoclasts at bone interface (resorption lacunae)
• No malignant transformation

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4. CLINICAL FEATURES

Symptoms

Signs on Otoscopy

Complications

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5. INVESTIGATIONS

Clinical / Audiological

Imaging

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6. MANAGEMENT

Non-Pharmacological (Conservative)

• Aural toilet / Suction clearance: Microsuction or direct removal of entrapped keratin in clinic — delays surgery, prevents accumulation and infection
• Saline irrigation: Irrigation to remove keratin from accessible retraction pockets
• Water precautions: Avoid water entry into infected ear; ear plugs for bathing
• Hearing aid: If hearing loss is significant and patient is not surgical candidate
• Regular follow-up: Essential — cholesteatoma can expand silently; 6–12 monthly otoscopy + audiometry

Conservative treatment is NOT curative — it is a temporizing measure. Cholesteatoma can only be eradicated by surgery.

Pharmacological

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7. SURGICAL TREATMENT

Overview of Surgical Approaches

1. Eradication of cholesteatoma (prevent recurrence/residual disease)
2. Management of complications
3. Hearing reconstruction (secondary)

• Resection & Reconstruction (canal-wall-up / CWU): cholesteatoma completely excised, ear canal rebuilt — includes attic resection, simple mastoidectomy, canal wall-up tympanomastoidectomy
• Exteriorization (canal-wall-down / CWD): ear anatomy altered to externalize disease — radical mastoidectomy, modified radical mastoidectomy (MRM), Bondy procedure

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SURGERY A: CANAL WALL-UP (CWU) TYMPANOMASTOIDECTOMY (Intact Canal Wall)

1. Patient supine, head turned, post-aural incision 1 cm behind pinna
2. Elevation of periosteum, identification of spine of Henle and linea temporalis
3. Cortical mastoidectomy: drill removal of mastoid cortex, opening mastoid antrum, identifying horizontal SCC and fossa incudis
4. Antral exposure — identify short process of incus and lateral SCC
5. Atticotomy — remove bone of lateral attic wall (scutum) to expose cholesteatoma in epitympanum
6. Dissection of cholesteatoma matrix — meticulous removal preserving ossicles if possible; cholesteatoma traced posteriorly through mastoid
7. Facial recess approach — drill posterior canal wall thinly, opening facial recess to expose sinus tympani and hypotympanum
8. Check ossicular chain — remove matrix from ossicles, assess ossicular continuity
9. Ossicular chain reconstruction (if needed): incus transposition, PORP/TORP prosthesis
10. Tympanoplasty: temporalis fascia graft underlay/overlay repair of TM
11. Cortical bone replaced or mastoid obliteration in selected cases
12. Closure in layers; wool/cotton pack in canal

• Antibiotics (oral/IV per contamination)
• Canal packing removed at 2–3 weeks
• Audiogram at 6–8 weeks
• Second-look surgery at 12 months to check for residual disease (or DWI-MRI as alternative)
• Regular outpatient follow-up

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SURGERY B: CANAL WALL-DOWN (CWD) — MODIFIED RADICAL MASTOIDECTOMY (MRM) / RADICAL MASTOIDECTOMY

• Radical mastoidectomy: removes entire posterior canal wall + middle ear mucosa; obliterates middle ear; no hearing reconstruction possible
• MRM (Bondy modification / standard MRM): posterior canal wall taken down, middle ear preserved where possible, TM remnant preserved, hearing reconstruction may be attempted

• HRCT temporal bone (essential for surgical planning)
• PTA + speech audiometry
• Informed consent: mastoid cavity, lifelong cleaning, water precautions, possible hearing loss, facial nerve risk
• Treat active infection preoperatively with topical antibiotics
• NPO, anaesthetic assessment, hair shaving

1. Post-aural incision; periosteum elevated
2. Mastoidectomy: all air cells exenterated, including tip cells, Trautmann's triangle
3. Lowering of the facial ridge: posterior canal wall drilled down to level of facial nerve — key step that externalizes the middle ear
4. Meatoplasty: enlarging the external meatus by removing conchal cartilage/skin to allow adequate cavity drainage and visualization
5. Removal of cholesteatoma matrix from middle ear
6. Saucerization: smoothing cavity walls to prevent ledges where epithelium can trap keratin
7. Tympanoplasty (in MRM): temporalis fascia or perichondrium used to reconstruct TM remnant; middle ear reconstructed if possible
8. In radical mastoidectomy: middle ear obliterated, Eustachian tube plugged
9. Cavity left open; cavity packed with bismuth iodoform paraffin paste (BIPP) or similar

• Pack removal at 2–3 weeks
• Cavity cleaning at 6 weeks, then 3-monthly
• Lifelong periodic microsuction of cavity (accumulation of keratin, moisture)
• Audiogram
• Water precautions (ear protection when swimming/bathing)
• No second-look surgery needed (cavity is externalized and directly visible)

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SURGERY C: ENDOSCOPIC EAR SURGERY (EES) — Modern adjunct

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Surgical Decision Summary Table

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Key Points Summary

• Cholesteatoma = destructive keratinizing squamous epithelial cyst; NOT a tumor
• Bone erosion via RANKL-mediated osteoclastogenesis (not pressure necrosis)
• Most common symptom: foul-smelling, scanty otorrhea
• Most common ossicular erosion: long process of incus
• Most common complication: labyrinthine fistula (horizontal SCC, 7–10%)
• Investigation of choice for residual post-op disease: Non-EPI DWI-MRI
• Definitive treatment: surgery only — no pharmacological cure
• Most common surgical approach: canal wall-up (preserves anatomy) vs canal wall-down (lower recurrence, cavity problems)

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CHOLESTEATOMA — Comprehensive Clinical Review

---

1. DEFINITION

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

---

2. ETIOLOGY — TABLE

---

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