Breast
Other carcinoma subtypes, WHO classified
Adenoid cystic


Topic Completed: 30 December 2019

Minor changes: 21 June 2020

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PubMed search: Adenoid cystic carcinoma[TI] breast free full text[sb]

Gary Tozbikian, M.D.
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Cite this page: Tozbikian G. Adenoid cystic. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmalignantadenoidcystic.html. Accessed November 30th, 2020.
Definition / general
  • Histologically similar to salivary gland counterpart
  • Triple negative and basal-like subtype of mammary carcinoma with excellent long term survival
Epidemiology
Diagnosis
  • Mammogram or other imaging detects a mass
  • Diagnosis made by tissue biopsy or resection, often utilizing immunohistochemistry
Radiology images

Contributed by Mark R. Wick, M.D.

Mammogram



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MRI

Prognostic factors
Case reports
Gross description
  • 1 - 3 cm, well circumscribed, firm
  • May have cystic cut surface
Microscopic (histologic) description
  • Dual population of cells (Arch Pathol Lab Med 1986;110:1045):
    1. Luminal / ductal epithelial cells with variable glandular / squamous / sebaceous differentiation
    2. Myoepithelial / basaloid cells
  • Cribriform, solid, tubular or trabecular architectural patterns
  • 2 types of lumens that are lined by 2 cell types:
    1. True glandular lumina lined by luminal / ductal epithelial cells (low molecular weight cytokeratin+, CK7+)
    2. Pseudolumens containing eosinophilic "cylinders" comprised of basement membrane material (laminin and collagen IV positive) lined by myoepithelial / basal type cells (p63 / p40+, smooth muscle myosin+, calponin+, high molecular weight cytokeratin+, S100+)
  • Solid variant: prominent basaloid features with more aggressive clinical course (Am J Surg Pathol 2002;26:413, APMIS 1999;107:762, BMJ Case Rep 2011;2011:bcr0820114692)
Microscopic (histologic) images

Contributed by Gary Tozbikian, M.D.

Adenoid cystic carcinoma


Adenoid cystic carcinoma

Estrogen receptor

p40

CD117 / KIT

Cytology description
  • Clusters of epithelial cells oriented around solid spheres of basement membrane material
Cytology images

Contributed by Mark R. Wick, M.D.

FNA



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Papanicolaou

Monomorphic tumor cells around mucoid material

Positive stains
Molecular / cytogenetics description
Differential diagnosis
Board review style question #1
A 55 year old woman undergoes an excision for a 3 cm breast mass (histologic image of the tumor is shown below). Which statement is true regarding this tumor?



  1. Frequently shows regional lymph node metastases
  2. Represents ~5% of all mammary cancers
  3. Triple negative for ER / PR / HER2 and has an aggressive clinical course
  4. Recurrent t(12;15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion is commonly seen
  5. CD117 / KIT expression is present in the luminal / ductal epithelial cell component
Board review answer #1
E. CD117 / KIT expression is present in the luminal / ductal epithelial cell component. The excision shows an adenoid cystic carcinoma, which is a rare subtype of mammary carcinoma representing < 1% of breast cancers. Despite triple negative status, these tumors generally show excellent long term survival. Similar to the salivary gland counterparts, adenoid cystic carcinomas of the breast are characterized by t(6;9)(q22-23;p23-24) translocation resulting in a MYB-NFIB fusion gene. The t(12;15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion (answer choice D) is seen in secretory carcinoma of the breast. Consistent CD117 / KIT protein expression is observed in most adenoid cystic carcinomas of the breast; however, underlying KIT gene alterations have not been identified (Histopathology 2013;62:543).

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Reference: Adenoid cystic carcinoma
Board review style question #2
Which immunohistochemical stain finding is typically observed in adenoid cystic carcinoma of the breast?

  1. CD117 / KIT positive, estrogen receptor positive
  2. CD117 / KIT negative, estrogen receptor negative
  3. MYB positive, estrogen receptor negative
  4. MYB positive, HER2 positive
  5. CD117 / KIT positive, HER2 positive
Board review answer #2
C. MYB positive, estrogen receptor negative. Adenoid cystic carcinoma of the breast is a biphasic tumor comprised of a ductal / epithelial cell and myoepithelial / basaloid cell components. The ductal / epithelial cells are immunoreactive for low molecular weight keratins such as CK7 and CK8/18. The myoepithelial / basaloid cell component is positive for high molecular weight keratins (CK5/6, CK14, CK17) and myoepithelial markers (p40 / p63, SMMS, calponin). Additionally, mammary adenoid cystic carcinomas generally express CD117 / KIT and MYB, and are triple negative for estrogen receptor, progesterone receptor and HER2.

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Reference: Adenoid cystic carcinoma
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