Skin nonmelanocytic tumor

Premalignant / in situ

Squamous cell carcinoma in situ / Bowen disease

Last author update: 1 June 2012
Last staff update: 31 March 2023

Copyright: 2002-2023,, Inc.

PubMed Search: Carcinoma in situ [title] skin

Christopher S. Hale, M.D.
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Cite this page: Hale CS. Squamous cell carcinoma in situ / Bowen disease. website. Accessed September 25th, 2023.
Definition / general
  • Usually on skin NOT exposed to sunlight, such as trunk
  • Called erythroplasia (of Queyrat) if at glans penis, vulva, oral cavity
  • Actinic keratosis with only a single layer of atypical keratinocytes may be invasive but Bowen disease seldom is
  • Mucosal variants in glans penis (penile intraepithelial neoplasia or "PIN") and vulva (vulvar intraepithelial neoplasia or "VIN") are associated with more aggressive behavior
Case reports
Gross description
  • Slightly raised, large scaly erythematous plaque with irregular border
  • Usually single patch or verrucous growth
Microscopic (histologic) description
  • By definition requires full thickness keratinocyte atypia, although may be surrounded by normal keratinocytes
  • Architectural and cellular atypia, apoptotic cells, individual cell dyskeratosis
  • Markedly altered maturation but usually still some surface keratinization and intercellular bridges present
  • Marked nuclear atypia, including nuclear hyperchromasia and multinucleation
  • Numerous mitotic figures, atypical mitotic figures
  • Also cytoplasmic vacuoles; rarely pagetoid cells or ground glass cytoplasm
  • May extend into eccrine sweat glands (not considered invasive disease)
  • Variable melanin, variable lymphocytic infiltrate
  • May have hemangiomatous vascular proliferation, amyloid globules, adnexal differentiation
Microscopic (histologic) images

Contributed by Amy Lynn, M.D., Andrey Bychkov, M.D., Ph.D. and Jijgee Munkhdelger, M.D., Ph.D.

Various images

Full thickness atypia

Hyperkeratosis and acanthosis

Pleomorphism, multinucleation

High power

Images hosted on other servers:

Various images

Differential diagnosis
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