External ear tumors - malignant

Squamous cell carcinoma

Last author update: 1 October 2013
Last staff update: 26 April 2023

Copyright: 2002-2023, PathologyOutlines.com, Inc.

PubMed Search: Squamous cell carcinoma external auditory canal

Nat Pernick, M.D.
Page views in 2022: 1,271
Page views in 2023 to date: 594
Cite this page: Pernick N. Squamous cell carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/earsccexternal.html. Accessed June 9th, 2023.
Definition / general
  • 15% of primary cutaneous carcinomas of external ear and auditory canal
  • Usually age 60+ years
  • Poor prognostic factors: > 2 cm, depth > 4 mm, poorly differentiated tumors, perineural invasion, development within a scar, previously treated squamous cell carcinoma at the site, immunosuppression, location within inner portion of canal with deep involvement of temporal bone
  • Tumor spread: tumors of helix spread along helix, to antihelix, to posterior surface of ear; tumors of antihelix spread concentrically; tumors of posterior surface spread to helix; tumors of canal tend to invade bone, may destroy tympanic membrane and penetrate middle ear
  • Adenoid squamous carcinoma:
    • Unusual variant
    • Also called pseudoglandular or acantholytic
    • Often face and scalp in sun exposed areas, particularly periauricular area
    • Due to a desmosomal defect that causes lack of cell adhesion (acantholysis)
Case reports
  • 65 year old woman with pigmented squamous cell carcinoma with dendritic melanocyte colonization in the external auditory canal (Pathol Int 1999;49:909)
  • 69 year old man with bilateral squamous cell carcinoma of the external auditory canals (Laryngoscope 2002;112:1003)
  • 72 year old man with bilateral auditory canal squamous cell carcinoma (HNO 2006;54:41)
  • 89 year old man with angiolymphoid hyperplasia with eosinophilia associated to a squamous cell carcinoma of the ear (Dermatol Surg 2004;30:1367)
  • Squamous cell carcinoma in situ of external auditory canal (J Laryngol Otol 2006;120:684)
  • Complete excision (mastoidectomy or temporal bone resection for canal tumors), possibly radiation therapy
  • Tumors of external ear have low recurrence rate (Dermatol Surg 2005;31:1423)
  • Canal tumors often recur (19%) or metastasize (11%); death may occur due to intracranial extension
Gross description
  • Polypoid, firm / rubbery nodules, frequent ulceration
Microscopic (histologic) description
  • Well differentiated:
    • Most common, composed of infiltrating nests of cells with keratin pearls or individual cell keratinization and intercellular bridges
    • Variable nuclear atypia
    • Frequent mitotic activity with atypical forms; invasion may be superficial with irregular budding of basal epithelium or irregular tongues of tumor projecting downward
  • Moderated differentiated:
    • Scattered individually keratinized cells; no keratin pearls
  • Poorly differentiated:
    • No obvious keratinization but squamous epithelial dysplasia, pavement-like cellular pattern, foci with intercellular bridges
  • Spindle cell variant:
    • Infiltrating tumor with interlacing bundles or fascicular growth
    • Spindled and epithelioid cells with amphophilic or eosinophilic cytoplasm, pleomorphic and hyperchromatic nuclei, increased N/C ratios, frequent mitotic activity with atypical forms
    • Often surface ulceration, surface epithelial dysplasia and differentiated squamous cell carcinoma
    • May produce chondroid or osteoid matrix
  • Adenoid squamous carcinoma:
    • Pseudoglandular appearance due to tumor cell acantholysis in center of tumor nests
    • Usually dysplastic surface epithelium
Microscopic (histologic) images

Contributed by Semir Vranic, M.D., Ph.D.
Missing Image Missing Image

Angiolymphatic invasion

Negative stains
  • Adenoid squamous carcinoma: mucin
Additional references
Back to top
Image 01 Image 02