Metaplastic carcinoma
Low grade adenosquamous

Minor changes: 24 November 2020

Copyright: 2001-2019,, Inc.

PubMed search: Adenosquamous [title] carcinoma breast

Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Low grade adenosquamous. website. Accessed November 25th, 2020.
Definition / general
  • Carcinoma with well developed tubule / gland formation mixed with widely dispersed solid nests of squamous cells
Clinical features
  • Uncommon; considered a rare variant of metaplastic breast carcinoma (Am J Surg Pathol 1987;11:351)
  • May originate from an intraductal papillary tumor, or be associated with sclerosing adenosis, radial scar or ductal adenoma
  • Recurs locally with conservative therapy, metastases unusual
  • Difficult to diagnose by fine needle aspiration, core biopsy or frozen section (Histopathology 2006;49:603)
Case reports
Gross description
  • Mean 2 - 3 cm, range 1 - 9 cm
  • Hard, tannish yellow, infiltrative
Gross images

AFIP Images

Well circumscribed mass

Microscopic (histologic) description
  • Resembles syringomatous adenoma of nipple; often originates from intraductal papillary tumor
  • Has tadpole or comma shaped epithelial structures with inner epithelial cells and outer myoepithelial cells
  • Also other areas of obvious squamous differentiation, desmoplastic stroma
  • Often keratinizing squamous component
Microscopic (histologic) images

AFIP images

Neoplastic ductules around a lobule

Neoplastic ductules with secretion and squamous area

DCIS in large duct
below / at arrows
giving rise to adeno-
squamous carcinoma

Invasive ductal elements
with syringomatous features
in dense collagenous stroma

Images hosted on other servers:

Various images

Various images

Cytology description
Positive stains
Negative stains
Electron microscopy description
  • Glandular and squamous differentiation
  • Squamous cells resemble acrosyringium of eccrine sweat gland
Differential diagnosis
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