Breast nonmalignant
Nonneoplastic changes

Topic Completed: 1 June 2010

Minor changes: 4 September 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Breast cysts [title]

Hind Warzecha, M.D.
Page views in 2019: 5,474
Page views in 2020 to date: 1,656
Cite this page: Warzecha H. Cysts . website. Accessed May 27th, 2020.
Definition / general
  • Round to ovoid structures of variable size, lined by an epithelium
  • Blue dome cysts: based on gross appearance
  • Type 1 cysts: Na/K ratio of 3 or less; increased breast cancer risk; associated with higher levels of estrogen, melatonin, epidermal growth factor and DHEA-S and lower levels of TGF-B2 than type 2 cysts (Breast Cancer Res Treat 2007;103:331)
  • Type 2 cysts: Na/K above 3: reduced breast cancer risk although patients may have both types of cysts and type 2 cysts can be associated with cancer (Breast 2005;14:37)
  • Note: type 1 and type 2 terminology is not commonly used
  • Very common nonproliferative breast lesion
  • Usually multifocal and bilateral
  • May arise from lobular acini that coalesce
Clinical features
  • Large cysts may present as a mass
  • Associated with microcalcifications on imaging
Case reports
Gross description
  • Variable size, usually visible grossly, contains clear or yellow fluid
Gross images

AFIP images

Large hemorrhagic cysts

Images hosted on other servers:

Unopened cyst

Extensive cystic disease

Large hemorrhagic cysts

Microscopic (histologic) description
  • Lined by double layer of flat / cuboidal cells or no lining
  • May rupture and elicit inflammatory response with foamy macrophages, cholesterol clefts, fibrosis
  • Variable apocrine metaplasia
Microscopic (histologic) images

AFIP images

Squamous metaplasia of epithelium lining cyst

Apocrine metaplasia of cyst lining

Images hosted on other servers:

Cysts in fibrocystic disease

Calcifications in cystically dilated ducts


Ultrasound and FNA of cyst
Differential diagnosis
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