Breast
Metaplastic carcinoma
Low grade adenosquamous


Minor changes: 22 December 2020

Copyright: 2001-2021, PathologyOutlines.com, Inc.

PubMed search: Adenosquamous [title] carcinoma breast

Paula S. Ginter, M.D.
Page views in 2020: 2,345
Page views in 2021 to date: 187
Cite this page: Ginter PS. Low grade adenosquamous. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastmalignantadenosquamous.html. Accessed January 23rd, 2021.
Definition / general
  • Rare variant of metaplastic carcinoma comprised of an intimately admixed combination of bland, well developed glands and solid squamous cell nests within a fibrotic or cellular spindle stroma
  • First reported in 1917 (Br J Surg 1917;5:417)
  • Formally recognized in 1987 (Am J Surg Pathol 1987;11:351)
Essential features
  • Rare variant of metaplastic carcinoma with low grade cytomorphology
  • Largely clinically indolent but may be locally aggressive
  • Diagnosis is based primarily on morphologic features, which can be challenging in small samples
  • Immunostaining patterns can be variable and unreliable
  • May arise in association with other breast lesions
Terminology
  • Syringomatous squamous tumor or infiltrative syringomatous adenoma
ICD coding
  • ICD-10: C50.919 - malignant neoplasm of unspecified site of unspecified female breast
Epidemiology
  • 0.2 to 1%
  • Median age: fifth decade; range: 20 - 85 years
  • Females; only one case report in male
Sites
  • Breast parenchyma
Pathophysiology
  • Unknown at this time
  • Association with other proliferative and sclerosing breast lesions has led some to suggest they represent precursors (Pathology 2014;46:402)
Etiology
  • Multifactorial
Clinical features
Diagnosis
  • Most frequently diagnosed via surgical resection
  • Difficult to diagnose by fine needle aspiration, core biopsy or frozen section (Histopathology 2006;49:603)
Radiology description
Radiology images

Images hosted on other servers:

Mammogram: asymmetry

Mammogram: calcifications

Mammogram: mass

Ultrasound: mass

Prognostic factors
Case reports
Treatment
  • Surgical excision with negative margins (Am J Surg Pathol 1987;11:351)
  • Radiotherapy is standard for patients with breast conserving surgery
  • Role of chemotherapy is indeterminate
Gross description
Gross images

Contributed by Paula S. Ginter, M.D.
Excisional biopsy of mass

Excisional biopsy of mass

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Paula S. Ginter, M.D.
Glands and squamous nests Glands and squamous nests Glands and squamous nests

Glands and squamous nests

Bland cytology Bland cytology

Bland cytology


Spindle stroma

Spindle stroma

Lymphoid aggregates

Lymphoid aggregates

Luminal keratin debris

Luminal keratin debris

Associated papilloma

Associated papilloma

Myosin: variable myoepithelial staining

Myosin: variable myoepithelial staining


p63: variable myoepithelial staining

p63: variable myoepithelial staining

CK7: core staining

CK7: core staining

ER negative

ER negative

Virtual slides

Images hosted on other servers:
Low grade adenosquamous carcinoma and DCIS

Low grade adenosquamous carcinoma and DCIS

p63: variable myoepithelial and luminal staining

p63: variable myoepithelial and luminal staining

ER negative (< 1%)

ER negative
(< 1%)

Cytology description
  • Variable cellular yield; not reliable as a surrogate for considering malignancy
  • Irregularly clustered cells, angulated sheets and tubular structures with monomorphic cytology (Acta Cytol 2014;58:427, Diagn Cytopathol 2012;40:713, Diagn Cytopathol 1999;20:13)
  • Whorl-like arrangements of epithelial cells may hint of squamous differentiation
  • Individually dispersed, atypical cells may be seen
  • Background may show mildly atypical naked nuclei and spindle cells (representing the stromal component)
  • Combination of epithelial and spindle elements is distinctive and should raise the possibility of low grade adenosquamous carcinoma
  • Accurate cytological identification is challenging
Positive stains
Negative stains
Electron microscopy description
Molecular / cytogenetics description
Sample pathology report
  • Left breast, 3 o'clock, lumpectomy:
    • Low grade adenosquamous carcinoma (see comment and synoptic report)
    • Ductal carcinoma in situ
    • Comment: Low grade adenosquamous carcinoma is grade 1 (2, 2, 1), measures 1.7 cm in greatest dimension, is associated with a sclerotic papilloma, is present less than 1 mm from the inked surgical margin and is ER negative (< 1%), PR negative (< 1%) and HER2 negative (0). No lymphovascular invasion identified. Ductal carcinoma in situ is solid type with intermediate nuclear grade and is present as a single 0.2 cm focus associated with the low grade adenosquamous carcinoma. Ductal carcinoma in situ is present > 2 mm from the inked surgical margin.
Differential diagnosis
Board review style question #1


Which of the following is true about low grade adenosquamous carcinoma of the breast?

  1. Associated with a poor prognosis
  2. Commonly estrogen receptor (ER) positive
  3. Consistent loss of myoepithelial cells by immunohistochemistry
  4. May be associated with other breast lesions
Board review style answer #1
D. May be associated with other breast lesions. Multiple reports have demonstrated an association of low grade adenosquamous carcinoma with other breast entities (i.e. papilloma, adenomyoepithelioma, radial scar / radial sclerosing lesions and fibroepithelial tumors). Low grade adenosquamous carcinoma is frequently ER negative. Low grade adenosquamous carcinoma demonstrates variable degrees of circumferential myoepithelial cell markers and immunohistochemistry is consistently inconsistent in this entity, limiting use. Low grade adenosquamous carcinoma is associated with a good prognosis.

Comment Here

Reference: Low grade adenosquamous
Back to top
Image 01 Image 02