Breast - nonmalignant
Benign tumors / changes
Hamartoma of breast

Author: Hind Nassar, M.D. (see Authors page)

Revised: 7 August 2017, last major update April 2010

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Hamartoma [title] breast [title]

Cite this page: Hamartoma of breast. website. Accessed September 21st, 2017.
Definition / general
  • Well circumscribed, often encapsulated mass composed of all components of breast tissue
  • Also called fibroadenolipoma, adenolipoma
  • May be a malformation, not a neoplasm
Radiology description
  • Xray: clearly demarcated lesion on mammography
Radiology images

Images hosted on PathOut server:

Mammogram, contributed by Dr. Mark R. Wick

Case reports
  • Excision; does not recur if negative margins
Gross description
  • Well circumscribed mass of firm, rubbery, white tissue, 1 - 8 cm, more distinctive grossly than microscopically
Gross images

Images hosted on PathOut server:

Ovoid yellow white mass

Images hosted on other servers:

Various images

Fat, glandular elements and stroma in pregnant patient

Smooth and glistening mass

Microscopic (histologic) description
  • Sharply circumscribed mass of disordered breast ducts and lobules
  • Ducts often dilated, accompanied by fibrosis
  • May have smooth muscle, adipose tissue, hyaline cartilage, pseudoangiomatous hyperplasia
  • May resemble gynecomastia due to lack of ducts
  • Myoid hamartoma: also has smooth muscle stroma; may contain epithelioid cells (Arch Pathol Lab Med 1996;120:676, Hum Pathol 1985;16:212)
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick

Adipose tissue plus ducts resembling gynecomastia

With ductal hyperplasia resembling gynecomastia

Smooth muscle bundles (arrows) and fibrous tissue

Hyaline cartilage and adipose tissue

Well defined
fibrous tumor,
ducts separated by
connective tissue

Images hosted on other servers:

Dilated ducts and fibrous stroma

Breast ducts and adipose tissue (adenolipoma)

Epithelial and mesenchymal components

Rounded border and fibrous capsule

Adipose normal lobules, cystically dilated ducts

Various images

With LCIS and invasive lobular carcinoma

Myoid hamartoma: H&E and smooth muscle actin+

Cytology description
  • Moderately cellular, sheets of bland ductal cells and lobular units, bipolar stromal nuclei, varying amounts of adipose tissue, less prominent stromal fragments, occasional apocrine and foamy cells, no atypia
  • Findings are not specific (Cancer 2003;99:255, Cytopathology 2003;14:195)
Differential diagnosis