Metaplastic carcinoma

Squamous cell carcinoma

Topic Completed: 1 August 2012

Minor changes: 27 September 2021

Copyright: 2002-2021,, Inc.

PubMed Search: squamous cell carcinoma breast

Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Squamous cell carcinoma. website. Accessed October 15th, 2021.
Definition / general
  • Primary breast carcinoma composed entirely of metaplastic squamous cells with variable keratin or spindle cells
  • Includes acantholytic squamous cell variant
  • Acantholytic squamous cell carcinoma also called pseudoglandular or adenoid squamous cell carcinoma
  • Acantholysis (lack of cell adhesion) is due to a desmosomal defect, possibly alteration in keratins (Cell Cycle 2008;7:2021)
Clinical features
Case reports
Gross description
  • May have central cyst with keratin
Gross images

AFIP images

Partially cystic tumor
(arrows at margins)

Images hosted on other servers:

Cystic area with necrosis (upper),
gray white solid area (below)

Microscopic (histologic) description
  • Tumor composed entirely of malignant squamous cells with variable keratinization and spindle cells
  • Bland squamous cells may line cystic spaces
  • May represent squamous metaplasia in ductal carcinoma
  • May have prominent myxoid stroma
  • Acantholytic subtype has pseudovascular or pseudoglandular appearance due to tumor cell discohesiveness, with lining composed of squamous epithelium and spaces with necrotic debris and keratin
Microscopic (histologic) images

Contributed by Dr. Mark R. Wick


Primary invasive


AFIP images

Poorly differentiated tumor with acantholysis and keratin pearl

Spaces between tumor cells may be mistaken for vessels

Squamous cell carcinoma
with transition to metaplastic
spindle cells and early
acantholytic changes

Images hosted on other servers:

Keratinizing tumor

Nonkeratinizing tumor

Nonkeratinizing tumor

Cytology description
Cytology images

Images hosted on other servers:

Polygonal tumor cells with abundant eosinophilic cytoplasm and nucleus hyperchromasia

Negative stains
Electron microscopy description
Differential diagnosis
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