Middle ear and inner ear tumors - benign / nonneoplastic


Topic Completed: 1 October 2013

Minor changes: 13 May 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

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

Nat Pernick, M.D.
Page views in 2020: 15,889
Page views in 2021 to date: 21,965
Cite this page: Pernick N. Cholesteatoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/earcholesteatoma.html. Accessed December 8th, 2021.
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)
External ear cholesteatoma
  • Resembles Keratosis obturans, but no osteonecrosis, no focal overlying epithelial loss (Clin Otolaryngol Allied Sci 2004;29:577)
  • Prognostic factors
    • Presence of papillary epithelial hyperplasia and marked koilocytosis is associated with aggressive disease and HPV (Med Sci Monit 2006;12:CR368)
    Case reports
    • 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:
    Missing Image

    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
    • External ear canal: cystic mass of keratinized squamous epithelium overlying area of bone sequestration in external auditory canal
    Microscopic (histologic) images

    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

    Differential diagnosis
    Back to top
    Image 01 Image 02