Breast nonmalignant
Benign tumors

Topic Completed: 1 March 2014

Revised: 30 May 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Fibroadenoma of the breast [title]

Hind Nassar, M.D.
Page views in 2018: 40,632
Page views in 2019 to date: 28,059
Cite this page: Nassar H Fibroadenoma. website. Accessed July 17th, 2019.
Definition / general
  • Benign biphasic tumor with epithelial and stromal components
  • Usually women age 30 years or less
  • Often in upper outer quadrant
  • Usually considered neoplastic; some believe it results from hyperplasia of lobular components
Clinical features
Radiology description
  • Xray: heavy, coarse calcifications
Radiology images

Contributed by Dr. Mark R. Wick:


Case reports
  • Excision (completely excise if 4 cm or more, enlarging over time and infiltrative border; after core biopsy, excise if cellular stroma found and phyllodes tumor cannot be excluded)
  • May "recur" if adjacent fibroadenomatous hyperplasia is present
  • Cryoablation (Am J Surg 2005;190:647)
  • Anti-estrogens (World J Surg 2007;31:1178)
Gross description
  • Sharply circumscribed with smooth, rounded border, freely movable spherical nodule, usually 3 cm or less
  • Gray white, bulging cut surface with numerous slits
  • 20% multifocal
Gross images

Contributed by Dr. Mark R. Wick:

Various images

Images hosted on other servers:

Various images

Multiple fibroadenomas

Well circumscribed mass

Microscopic (histologic) description
  • Rounded contour, overgrowth of fibrous and glandular tissue
  • Intralobular stroma (delicate, cellular, myxoid or fibrotic) encloses glandular spaces; may infarct, become inflamed, calcify
  • Pericanalicular: open glandular spaces vs intracanalicular: compressed glandular spaces (no clinical significance to this distinction)
  • Glands have cuboidal / low columnar epithelium and adjacent myoepithelium but no atypia
  • 15% have apocrine metaplasia
  • May have myxoid change (suggests Carney syndrome), sclerosing adenosis, epithelial hyperplasia or other fibrocystic change
  • May have adjacent fibroadenomatous change
  • Rarely has pleomorphic, bizarre multinucleated giant cells (Arch Pathol Lab Med 2000;124:1721, Diagn Pathol 2008;3:33, Am J Surg Pathol 1986;10:823, Arch Pathol Lab Med 1994;118:912), squamous metaplasia, smooth muscle or adipose tissue, metaplastic cartilage, DCIS or LCIS
  • Fibroadenoma phyllodes: rarely has focal leaf-like processes but otherwise typical fibroadenomatous stroma
  • No necrosis, no elastic tissue, no anaplasia, no mitotic figures
Microscopic (histologic) images

Scroll to see all images:

Contributed by Dr. Mark R. Wick:

Various images

Containing DCIS

Case of the Week #37:

Atypical stromal cells

AFIP images:

Epithelial hyperplasia


With adenosis

Smooth muscle

Squamous metaplasia

Images hosted on other servers:

Fibroblastic stroma surrounding compressed ducts

Intracananlicular pattern

Pericanalicular pattern

Mild hypercellularity

With apocrine change

Infarcted fibroadenoma, contributed by Dr. Semir Vranić, University of Sarajevo (Bosnia)

With cystic changes

Epithelial hyperplasia

With atypical lobular hyperplasia

With colloid (mucinous) carcinoma


With infiltrating ductal carcinoma

Fibroadenoma with LCIS and invasive lobular carcinoma (contributed by Semir Vranić, MD)

Core biopsies

Digital fibroma-like inclusions

Various immunostains

Fig 2: Fibroadenoma
Fig 3: Giant cells
Fig 4: Vimentin

With papillary carcinoma


Myxoid stroma

Bizarre stromal giant cells

Stromal edema

Virtual slides

Images hosted on other servers:


Cytology description
Cytology images

Images hosted on other servers:

Various images


Fig 1: Multiple masses in mammogram
Fig 2, 3: FNA shows sheets and clusters of ductal cells and
myoepithelial cells with background myxoid stroma
Fig 4: Classic features at core biopsy

Positive stains
Stromal cells
Epithelial cells
Electron microscopy description
  • Basal lamina around epithelial and endothelial cells
Molecular / cytogenetics description
  • Clonal chromosomal aberrations in 20%

Differential diagnosis
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