Metaplastic carcinoma

Topic Completed: 1 September 2012

Minor changes: 22 December 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Metaplastic carcinoma [title] breast

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Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Metaplastic. website. Accessed March 4th, 2021.
Definition / general
  • Heterogeneous group of neoplasms with predominant component other than epithelial / glandular
  • Also called carcinosarcoma (if mesenchymal component is malignant), carcinoma with osteoclastic giant cells and carcinoma with osseous metaplasia
  • "Metaplastic" due to the transformation of epithelial component into a non-glandular component, such as spindle cells, squamous cells or heterologous elements
Clinical features
  • Uncommon (< 5% of breast carcinomas)
  • More aggressive than invasive ductal NOS due to larger tumor size, higher grade
  • Metastases tend to be hematogenous and not nodal (Ann Surg Oncol 2007;14:166, Breast Cancer Res Treat 2007;101:349)
  • Represents a type of basal-like carcinoma lacking epidermal growth factor receptor and KIT activating mutations, but exhibiting high epidermal growth factor receptor copy number, primarily via aneusomy (Mol Cancer Ther 2008;7:944)
Case reports
  • Mastectomy or local excision
Gross description
  • Well-circumscribed
  • Median 3 - 4 cm, range 1 - 21 cm
  • Usually firm, nodular
  • Squamous or chondroid areas are pearly white to gray glistening areas on cut surface
Gross images

AFIP images

Bisected squamous tumor (arrows at tumor margin)

Carcinoma with osteoclast-like giant cells

Images hosted on other servers:

Causing skin ulceration

Sharply circumscribed tumor

Microscopic (histologic) description
  • Sarcomatous component resembles fibromatosis (see variant), fibrosarcoma, malignant fibrous histiocytoma, chondrosarcoma or osteosarcoma (see variant), rhabdomyosarcoma, spindle cells (see variant), angiosarcoma or combination
  • May need to look carefully for epithelial component (may be ductal carcinoma in situ or invasive ductal carcinoma), may have osteoclast-like giant cells (Hum Pathol 1990;21:142)
  • Some classify as "with squamous metaplasia" or "with heterologous metaplasia"
  • Recommended to test any keratin negative stromal tumor of the breast with myoepithelial markers before calling it a primary sarcoma (Am J Surg Pathol 2005;29:347)
Microscopic (histologic) images
Contributed by Indu Agarwal M.D.
Missing Image Missing Image

Chondroid differentiation

Case of the Week #6

AFIP images

Well differentiated
carcinoma and
poorly differentiated
merge with the
spindle cell component

with a tubular pattern
in the metaplastic
spindle cell component

glands are surrounded
by an undifferentiated
round cell proliferation
that merges with the
spindle cells

Transition from
adenocarcinoma to
spindle cell pattern

Poorly differentiated
carcinoma with traces
of squamous metaplasia
giving rise to the spindle
cell component

Invasive adenocarcinoma
at upper right, but most
tumor is solid
metaplastic elements with
pale, serpiginous areas
of necrosis

Adenocarcinoma with
transition to undifferentiated
carcinoma, an intermediate
step in conversion to
spindle cell metaplasia

Recurrent metaplastic
carcinoma 4 years after
mastectomy, tumor was
initially interpreted as a
radiation induced sarcoma

Resembles giant cell tumor of bone due to osteoclast-like giant cells

Osteoclast-like giant
cells in stroma associated
with the carcinoma component

Contributed by Dr. Semir Vranic

Squamous component

EGFR expression

Images hosted on other servers:

Various images

Case #294

Keratin+ cells



EGFR and HER2 over expression in spindle cell carcinoma

Various images

Cytology description
Positive stains
Molecular / cytogenetics description
  • Epithelial and sarcoma components originate from same clone
  • Epidermal growth factor receptor overexpression in 2/3, 1/3 of these have EGFR gene amplification, but no activating EGFR mutations (J Pathol 2006;209:445)
Differential diagnosis
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