Fibrocystic changes

Topic Completed: 1 February 2015

Minor changes: 20 October 2020

Copyright 2002-2020,, Inc.

PubMed Search Adenosis [title] breast [title]

Jaya Ruth Asirvatham, M.B.B.S.
Julie M. Jorns, M.D.
Page views in 2019: 13,779
Page views in 2020 to date: 10,810
Cite this page: Asirvatham JR, Jorns JM. Adenosis. website. Accessed October 20th, 2020.
Definition / general
  • Any hyperplastic process (see subtypes below) primarily involving glands (i.e. an increased number of glandular components)
  • Common, benign, often accompanied by fibrosis
  • Premenopausal: lesions with predominant epithelial component (proliferation of acini and ducts); nodular adenosis
  • Postmenopausal: lesions with more sclerosis (sclerosing adenosis)
  • Not specific
  • Part of fibrocystic changes
Clinical features
  • Can present as a mass (as nodular adenosis or adenosis tumor) or as calcifications on imaging
Prognostic factors
  • With some types (sclerosing adenosis), the risk of subsequent breast cancer is 1.5 - 2x higher
  • Does not require treatment if there is no cytologic atypia
Microscopic (histologic) description
  • See also separate topics for each subtype
  • Apocrine adenosis: adenosis with predominant apocrine cytology
  • Microglandular adenosis: nonlobulocentric proliferation of mammary glands with an infiltrative pattern, lined by a single epithelial layer with a basement membrane
  • Sclerosing adenosis: lobulocentric proliferation of glands (2 layers) with glandular compression and distortion due to stromal proliferation
  • Simple adenosis: loosely structured proliferation of acinar or tubular structures, with epithelial and myoepithelial layers, surrounded by basement membrane, without distortion of lobular architecture
  • Tubular adenosis: haphazard proliferation of branching tubules (2 layers)
Microscopic (histologic) images

Contributed by Dr. Mark R. Wick

Blunt ductal

Columnar cell change

Nodular / sclerosing


AFIP images

Reticulin stain,
continuous basement
around glands

Differential diagnosis
  • Invasive carcinoma: mainly an issue in cases of sclerosing, tubular and microglandular adenosis
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