Breast hamartoma

Breast hamartoma (also known as a fibroadenolipoma) is a benign breast lesion.

They typically occur in women older than 35 years of age. 

While it can present as a painless soft lump, it may also present as unilateral breast enlargement without a palpable localised mass lesion 4.

It results from a benign proliferation of fibrous, glandular, and fatty tissue (hence fibro-adeno-lipoma) surrounded by a thin capsule of connective tissue. All components are found in normal breast tissue (hence the term hamartoma).

Macroscopically, hamartomas are slightly larger and softer than common adenofibromas and, are well-defined, whitish, pinkish and fleshy, with islands of yellow fat tissue. Histologically, they exhibit pushing borders with a pseudo-encapsulation, and consist of a combination of variable amounts of stromal and epithelial components.

Lesions can be any size but are typically large at presentation.

Typically seen as a well-circumscribed, round to oval inhomogeneous mass surrounded by a thin capsule, comprising of both fat and soft-tissue densities (both radiolucent and radiodense components). Sometimes this is described as a "breast within a breast"  or a "slice of sausage" appearance.

Because it resembles the normal breast tissue usually it is difficult to delineate the margins. It may be seen as a well-circumscribed, solid lesion without any intralesional microcalcification. Internal echotexture most often mixed with both hyperechoic and hypoechoic components 3. Lesions are soft and easy to compress.

It was initially described by M G Arrigoni in 1971 2 

Breast imaging and pathology
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Article information

rID: 10593
System: Breast
Section: Pathology
Synonyms or Alternate Spellings:
  • Breast fibroadenolipoma
  • Fibroadenolipoma of breast
  • Hamartoma of breast
  • Hamartoma of the breast
  • Breast hamartomas

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