Breast
Fibrocystic changes
Microcysts


Topic Completed: 1 June 2010

Minor changes: 26 August 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Breast cysts [title]

Hind Warzecha, M.D.
Page views in 2019: 5,474
Page views in 2020 to date: 3,271
Cite this page: Warzecha H. Microcysts . PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastcysts.html. Accessed November 23rd, 2020.
Definition / general
  • Round to ovoid structures of variable size, lined by an epithelium
Terminology
  • 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
Epidemiology
  • Very common nonproliferative breast lesion
Sites
  • Usually multifocal and bilateral
Etiology
  • May arise from lobular acini that coalesce
Clinical features
  • Large cysts may present as a mass
  • Associated with microcalcifications on imaging
Case reports
Treatment
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

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

Videos


Ultrasound and FNA of cyst
Differential diagnosis
Back to top
Image 01 Image 02