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Breast

Other invasive carcinoma subtypes, WHO classified

Adenoid cystic

Author: Gary Tozbikian, M.D.

Editorial Board Member: Kristen E. Muller, D.O.

Editor-in-Chief: Debra L. Zynger, M.D.

Last author update: 16 May 2023

Last staff update: 16 May 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Adenoid cystic carcinoma breast

Table of Contents

Cite this page: Tozbikian G. Adenoid cystic. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastmalignantadenoidcystic.html. Accessed December 26th, 2024.

Definition / general

Histologically similar to salivary gland counterpart
Triple negative and basal-like subtype of mammary carcinoma with excellent long term survival

Essential features

Rare subtype of breast cancer, histomorphologically identical to salivary gland counterpart
Comprised of epithelial and myoepithelial cells arranged in solid, cribriform or tubular arrangements and associated basement membrane material
Associated with MYB::NFIB fusion

ICD coding

ICD-10: C50.91 - malignant neoplasm of breast of unspecified site, female

Epidemiology

Rare, 0.1% of breast carcinomas (Am J Surg 2002;183:646)
Mean age: 64 years; range: 25 - 80 years (Breast Cancer Res 2010;12:R54)
May be associated with microglandular adenosis (Am J Surg Pathol 2003;27:1052)

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

Images hosted on other servers:

MRI

Prognostic factors

Low rates of recurrence and better long term outcome compared with ductal NOS type (Breast 2012;21:124, Breast Cancer Res Treat 2004;87:225, Breast Cancer Res 2010;12:R54, J Clin Pathol 2010;63:220)
High rates of margin positivity (Am J Clin Oncol 2010;33:28)
Axillary nodal metastases are rare, more frequently seen in the solid variant (Am J Surg Pathol 2002;26:413)
Treatment is excision with clear margins and possibly radiation; axillary dissection may not be necessary (J Surg Oncol 2010;102:342, Breast 2017;31:214)

Case reports

21 year old man with left nipple swelling (Breast J 2020;26:502)
56 year old woman with a breast mass (Case Rep Oncol 2019;12:698)
63 year old woman with a breast mass (J Surg Case Rep 2019;2019:rjy355)
65 year old woman with a breast mass, metastases to lung, kidney and brain (J Med Case Rep 2017;11:303)
69 year old woman with a breast mass (Ann Med Surg (Lond) 2019;43:1)
71 year old woman with a breast mass (Int J Surg Case Rep 2018;42:196)
85 year old woman with a breast mass (J Med Invest 2018;65:289)

Gross description

1 - 3 cm, well circumscribed, firm
May have cystic cut surface
Reference: Pathology 2017;49:215

Microscopic (histologic) description

Dual population of cells (Arch Pathol Lab Med 1986;110:1045):
- Luminal / ductal epithelial cells with variable glandular / squamous / sebaceous differentiation
- Myoepithelial / basaloid cells
Cribriform, solid, tubular or trabecular architectural patterns
2 types of lumens that are lined by 2 cell types
- True glandular lumina lined by luminal / ductal epithelial cells (low molecular weight cytokeratin+, CK7+)
- 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+)
Histologic variants
- Classic variant: most frequent variant, low to intermediate nuclear grade, composed of mixture of 3 different architectural patterns (tubular, cribriform and solid) (Diagn Histopathol 2022;28:142)
- Solid - basaloid variant: solid nests, increased mitotic rate, presence of necrosis, Ki67 > 30%, 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, Int J Surg Pathol 2016;24:97)
- Adenoid cystic carcinoma with high grade transformation: associated with different higher grade component subtypes such as invasive breast cancer of NST type (Int J Surg Pathol 2011;19:230)

Microscopic (histologic) images

Contributed by Gary Tozbikian, M.D.

Extensive cribriform architecture, infiltrative growth pattern

Dual population of basaloid and epithelioid cells

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.

FNAB

Images hosted on other servers:

Papanicolaou

Monomorphic tumor cells around mucoid material

Positive stains

Luminal / ductal epithelial cells
Basaloid / myoepithelial type cells
Secretions in true lumina
- PAS+ diastase resistant
Cribriform spaces
- Alcian blue (Am J Clin Pathol 2005;124:733)
Pseudolumen secretions
- Laminin
- Collagen IV

Negative stains

Estrogen receptor, progesterone receptor (usually), HER2 (Mod Pathol 2005;18:1277)
TRPS1 (Hum Pathol 2022;125:97)

Molecular / cytogenetics description

MYB::NFIB fusion gene (t(6;9)(q22-23;p23-24)) identified in the majority adenoid cystic carcinomas of breast, as well as in solid variant (J Pathol 2012;226:84, Proc Natl Acad Sci U S A 2009;106:18740, Hum Pathol 2014;45:2270)
Molecular profiling of adenoid cystic carcinomas assign them to the basal-like subtype but have lower genetic instability and copy number aberrations compared with metaplastic, medullary and basal-like no special type (NST) tumors (Breast Cancer Res Treat 2013;142:257, Histopathology 2013;62:543, J Pathol 2008;216:141)
Solid - basaloid variant: NOTCH and CREBB mutations (Mod Pathol 2020;33:1041)

Sample pathology report

Left breast, mass 10:00, ultrasound guided core needle biopsy:
- Adenoid cystic carcinoma, 1.2 cm in greatest length (see comment)
- Estrogen receptor: negative (0%, no intensity)
- Progesterone receptor: negative (0%, no intensity)
- HER2: negative (score 0)
- Comment: Additional immunohistochemical stains show that the tumor is positive for CD117, MYB and p40 (in basaloid cells), supporting the diagnosis.

Differential diagnosis

Collagenous spherulosis:
- Noninfiltrative proliferation of myoepithelial cells enclosing basement membrane material confined within preexisting ducts / lobules and lacking epithelial cell component
- Lacks dual cell population
- Calponin+, smooth muscle myosin heavy chain / SMMHC+, CD117 / KIT- (Mod Pathol 2006;19:1351)
Invasive cribriform carcinoma:
- Infiltrative glands lack circumscription by myoepithelial cells (myoepithelial cells limited to periphery of ducts involved by ductal carcinoma in situ component)
- Lacks dual cell population
- Estrogen receptor+, progesterone receptor+, CD117 / KIT-

Additional references

Am J Surg Pathol 1998;22:569, Hum Pathol 1987;18:1276, Mod Pathol 1996;9:215, Stanford University: Adenoid Cystic Carcinoma of the Breast [Accessed 8 February 2023]

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 above). Which statement is true regarding this tumor?

CD117 / KIT expression is present in the luminal / ductal epithelial cell component
Frequently shows regional lymph node metastases
Recurrent t(12;15)(p13;q25) translocation resulting in ETV6::NTRK3 gene fusion is commonly seen
Represents ~5% of all mammary cancers
Triple negative for ER / PR / HER2 and has an aggressive clinical course

Board review style answer #1

A. 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 C) 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?

CD117 / KIT negative, estrogen receptor negative
CD117 / KIT positive, estrogen receptor positive
CD117 / KIT positive, HER2 positive
MYB positive, estrogen receptor negative
MYB positive, HER2 positive

Board review style answer #2

D. 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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