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Cholesteatoma

Summary

  • Cholesteatoma is a benign but locally destructive lesion of the temporal bone, characterised by an accumulation of keratinizing squamous epithelium
  • It typically presents with chronic otorrhea, hearing loss, and potential complications due to erosion of surrounding structures
  • Imaging plays a crucial role in diagnosis, surgical planning, and follow-up

Pathophysiology

  • Two main types:
    • Congenital: Remnant of embryonic epithelial tissue in the middle ear
    • Acquired: Most common, develops from retraction pocket in pars flaccida of tympanic membrane
  • Growth occurs through accumulation of desquamated keratin and debris
  • Expansion leads to bone erosion through pressure necrosis and enzymatic activity

Demographics

  • Incidence: 3 per 100,000 in children, 9.2 per 100,000 in adults
  • Slightly more common in males
  • Peak incidence in second and third decades of life
  • Risk factors:
    • Chronic otitis media
    • Eustachian tube dysfunction
    • Craniofacial abnormalities (e.g., cleft palate)

Diagnosis

  • Clinical presentation:
    • Chronic otorrhea
    • Progressive conductive hearing loss
    • Otalgia
    • Vertigo (in advanced cases)
  • Otoscopic examination:
    • Retraction pocket or attic perforation
    • White or pearly mass behind tympanic membrane
  • Audiometry:
    • Conductive hearing loss
    • Sensorineural component in advanced cases

Imaging

  • CT (non-contrast):
    • Modality of choice for initial evaluation and surgical planning
    • Findings:
    • Soft tissue mass in middle ear or mastoid
    • Bone erosion (scutum, ossicles, tegmen tympani)
    • Widening of aditus ad antrum
    • Labyrinthine fistula (in advanced cases)
  • MRI:
    • Complementary to CT, especially for follow-up and recurrence detection
    • Findings:
    • T1: Intermediate to low signal intensity
    • T2: Heterogeneous, predominantly high signal intensity
    • Diffusion-weighted imaging (DWI): Restricted diffusion, high signal on b1000 images
  • Non-echo planar diffusion-weighted imaging (non-EPI DWI):
    • Higher sensitivity for small cholesteatomas and recurrence detection

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  • A 20-year-old patient presented with a facial nerve palsy and sensorineural hearing loss.
  • CT showed erosion of the petrous bone including the posterior wall of the internal auditory canal and the wall of the labyrinthine and tympanic facial canal.
  • MRI showed a non-enhancingm and T2-hyperintense lesion causing diffusion restriction.

Treatment

  • Surgical management is the mainstay of treatment
  • Surgical approaches:
    • Canal wall up (CWU) tympanomastoidectomy
    • Canal wall down (CWD) tympanomastoidectomy
  • Choice of approach depends on extent of disease and surgeon preference
  • Goals of surgery:
    • Complete removal of cholesteatoma
    • Preservation or reconstruction of hearing mechanism
    • Prevention of recurrence
  • Postoperative follow-up:
    • Regular otoscopic examinations
    • Audiometry
    • Imaging (CT or MRI) to detect recurrence
  • Complications if left untreated:
    • Intracranial extension
    • Facial nerve paralysis
    • Labyrinthine fistula
    • Meningitis
    • Brain abscess

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Chronic otitis media Lack of keratin debris on imaging
Epidermoid cyst Markedly restricted diffusion; typically occurs in CPA cistern or other extra-otologic sites
Paraganglioma Characteristic "salt and pepper" appearance on MRI
Cholesterol granuloma Hyperintense on T1-weighted MRI
Langerhans cell histiocytosis Typically multifocal lesions