Fibroepithelial tumors


Editorial Board Member: Julie M. Jorns, M.D.
Deputy Editor-in-Chief: Gary Tozbikian, M.D.
Indu Agarwal, M.D.
Luis Blanco, Jr., M.D.

Last author update: 9 May 2022
Last staff update: 9 May 2022

Copyright: 2002-2024,, Inc.

PubMed Search: Breast hamartoma

Indu Agarwal, M.D.
Luis Blanco, Jr., M.D.
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Cite this page: Agarwal I, Blanco L. Hamartoma. website. Accessed April 14th, 2024.
Definition / general
  • Well circumscribed, often encapsulated mass composed of normal but disorganized components of breast tissue
Essential features
  • Uncommon breast mass lesion that contains normal breast elements in varying proportions
  • Clinically presents as painless lump or detected via breast imaging
  • Microscopy shows well circumscribed mass with normal breast components (e.g., mammary glands, adipose tissue and fibrous stroma)
  • Definitive diagnosis on core needle biopsy requires correlation with imaging
  • First described by Hogeman and Ostberg in 1968; term first used by Arrigoni in 1971 (Sem Hop 1976;52:1405)
  • Acceptable by WHO: adenolipoma, chondrolipoma, myoid hamartoma
  • Not recommended by WHO: fibroadenolipoma, adenolipofibroma
  • Uncommon; < 5% of all benign breast masses (Histopathology 2022;80:304)
  • Predominantly women in fifth decade but can be seen at any age
  • No specific location in the breast
  • Largely unknown; unclear whether a malformation or neoplasm
  • Mostly sporadic; rarely associated with Cowden syndrome (multiple hamartomas)
Clinical features
  • Presents as painless breast mass or detected by screening mammography or other breast imaging modalities
  • Mammographic or sonographic abnormality
  • Often cannot be definitively diagnosed on core needle biopsy; excisional biopsy is more definitive
Radiology description
Radiology images

Images hosted on other servers:
Mammographic findings

Mammographic findings

Prognostic factors
  • Rarely recurs; reported recurrences represent incomplete excisions (Aust J Gen Pract 2019;48:275)
  • No increase in malignancy (same malignant potential as normal breast tissue)
Case reports
  • Surgical excision is curative but not necessary
Gross description
  • Well circumscribed, round to oval, range 1 - 14 cm; may resemble normal breast tissue, lipoma or fibroadenoma
Gross images

Images hosted on other servers:

Cut section of mammary hamartoma

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Indu Agarwal, M.D.

Mammary hamartoma

Components of mammary hamartoma Components of mammary hamartoma

Components of mammary hamartoma

Myoid hamartoma Myoid hamartoma

Myoid hamartoma

Myoid hamartoma, immunostain desmin

Myoid hamartoma, immunostain desmin

Myoid hamartoma, immunostain SMA

Myoid hamartoma, immunostain SMA

Cytology description
  • Moderately cellular, bland epithelial and stromal components
  • Diagnosis limited as findings are not specific (J Clin Pathol 2002;55:951)
Positive stains
Molecular / cytogenetics description
Sample pathology report
  • Left breast, mass at 11 o'clock, ultrasound guided core needle biopsy:
    • Consistent with mammary hamartoma (see comment)
    • Comment: A well circumscribed lesion is seen comprised of benign breast elements arranged in a disorganized manner. In light of the known breast mass seen on imaging, findings are consistent with a mammary hamartoma.
Differential diagnosis
  • Fibroadenomas:
    • In fibroadenoma, the epithelial elements often show more proliferative changes (e.g., usual type ductal hyperplasia, apocrine metaplasia)
    • Fibroadenomas only rarely include adipose tissue
  • Phyllodes tumor:
    • Hypercellular stromal component, stromal atypia, frond formation, may show infiltrative borders
Board review style question #1

A 45 year old woman presents for screening mammogram and a multilobulated 1.5 cm mass is detected. Ultrasound confirms the findings and a guided core needle biopsy is performed, which shows normal breast ducts, lobules, fibrous stroma and adipose tissue. The radiologist confirms that the lesion was biopsied. What is the most likely possibility?

  1. Angiolipoma
  2. Breast hamartoma
  3. Myofibroblastoma
  4. Radiologist missed the lesion
Board review style answer #1
B. Breast hamartoma. The mass lesion by imaging and the histologic finding of normal breast components with somewhat disorganized architecture support this diagnosis. Also, since the radiologist was confident that the lesion was biopsied, the possibility that the lesion was missed is excluded.

Comment here

Reference: Hamartoma
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