Middle ear, inner ear and temporal bone tumors - benign / nonneoplastic

Topic Completed: 1 October 2013

Revised: 28 August 2019

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PubMed Search: Cholesteatoma [title] ear pathology review[ptyp]

Nat Pernick, M.D.
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Cite this page: Pernick N. Cholesteatoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/earcholesteatoma.html. Accessed December 5th, 2019.
Definition / general
  • Also called keratoma (more accurate term), epidermal inclusion cyst of middle ear
  • Stratified squamous epithelium that forms saclike accumulation of keratin within middle ear space
  • Usually men, ages 20s to 30s
  • May be (a) congenital (squamous epithelium is trapped within temporal bone during embryogenesis; tympanic membranes are intact; no history of infections), (b) primary acquired (retraction of tympanic membrane), (c) secondary acquired (due to injury to tympanic membrane)
  • May cause progressive bone erosion of ossicles and surrounding bone but is not neoplastic; incomplete excision may lead to widespread bone destruction
  • Damage apparently is due to associated inflammation and proteolytic enzymes, not pressure from tumor mass (Mod Pathol 2001;14:1226)
  • Aural polyps composed of granulation tissue and with keratin flakes or masses are usually associated with underlying cholesteatoma (J Clin Pathol 1989;42:460)
Prognostic factors
  • Presence of papillary epithelial hyperplasia and marked koilocytosis is associated with aggressive disease and HPV (Med Sci Monit 2006;12:CR368)
  • Complete excision of all components
Gross description
  • Cystic, white masses of varying size with creamy or waxy granular material
Gross images

Images hosted on other servers:
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Yellow white waxy material

Microscopic (histologic) description
  • Keratinized stratified squamous epithelium (required for diagnosis) with granulation tissue and keratin debris
  • Chronic inflammatory infiltrate, cholesterol clefts, foreign body giant cell granulomas, hemosiderin
  • No dysplasia
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Kelly Magliocca D.D.S., M.P.H.

Inflamed middle ear mucosa

Residual fibrous tissue and underlying cartilage

Middle ear mucosa with hyperplasia

Cuboidal middle ear epithelium

Keratinizing stratified squamous epithelium

Keratin granuloma within ossicular tissue

Images hosted on other servers:
Missing Image

Squamous epithelium with keratin debris

Differential diagnosis
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