Breast
Fibrocystic changes
Sclerosing adenosis

Editorial Board Member: Gary Tozbikian, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Julie M. Jorns, M.D.

Minor changes: 13 April 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Sclerosing adenosis [title] breast

Julie M. Jorns, M.D.
Page views in 2020: 13,754
Page views in 2021 to date: 5,582
Cite this page: Jorns JM. Sclerosing adenosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastsclerosingadenosis.html. Accessed April 18th, 2021.
Definition / general
  • Adenosis or lobulocentric processes with increase in glandular elements of terminal duct lobular unit (TDLU) with stromal fibrosis / sclerosis that distorts and compresses glands
  • Preserved 2 cell layer (inner epithelial and outer myoepithelial cells)
Essential features
  • Enlarged terminal duct lobular unit with distortion by stromal fibrosis / sclerosis
Terminology
ICD coding
  • ICD-10:
    • N60.3 - fibrosclerosis, breast
    • N60.8 - other benign mammary dysplasias
  • ICD-11:
    • GB20.Y - other specified benign breast disease
    • GB20.Z - benign breast disease, unspecified
Epidemiology
  • Most frequent in third to fourth decades but occurs over a wide age range
  • Found in 12 - 28% of all benign and 5 - 7% of malignant biopsies (J Ultrasound Med 2013;32:2029)
Sites
  • Terminal duct lobular unit; otherwise, no specific location within the breast
Pathophysiology
  • Unknown
Etiology
  • Unknown
Clinical features
Diagnosis
  • Histologic examination of tissue with or without immunohistochemistry
Radiology description
Radiology images

Contributed by Julie M. Jorns, M.D.
Calcifications, craniocaudal view

Calcifications, craniocaudal view

Calcifications, mediolateral oblique view

Calcifications, mediolateral oblique view

Prognostic factors
Case reports
Treatment
  • Presence of sclerosing adenosis alone in a core biopsy does not require surgical excision
  • Coexisting atypia will typically prompt surgical consultation
Gross description
  • Variable depending on extent of involvement and calcifications
  • May be indistinguishable from surrounding breast tissue
  • Multinodular, ill defined, cuts with increased resistance due to fibrosis
  • Gritty due to frequent calcifications but no chalky yellow white foci or streaks as seen in fat necrosis
  • Circumscribed to ill defined white, fibrotic mass if nodular adenosis / adenosis tumor
  • Reference: Schnitt: Biopsy Interpretation of the Breast, 3rd Edition, 2017
Microscopic (histologic) description
  • Low power: increase in glandular elements plus stromal fibrosis / sclerosis that distorts and compresses glands
  • Maintains lobular architecture at low power with rounded and well defined nodules
  • Centrally is more cellular with distorted and compressed ductules; peripherally has more open or dilated ductules
  • Often has microcalcifications, due to calcification of entrapped secretions
  • Often has associated fibrocystic changes of other types, such as apocrine metaplasia
  • Preservation of luminal epithelium and peripheral myoepithelium (2 cell layer) with surrounding basement membrane
  • Myoepithelial cells may vary from being prominent to indistinct on routine H&E staining
  • Myoepithelial cells are readily apparent via immunohistochemistry, even if difficult to identify on H&E
  • Rarely penetrates walls of blood vessels or perineural spaces
  • No necrosis, no pleomorphism
  • Apocrine adenosis: variant of sclerosing adenosis with prominent apocrine features
  • Epithelium may be involved by proliferative, atypical lesions or in situ carcinoma
  • Can mimic malignancy:
    • If involved by atypia or in situ carcinoma
    • If florid and overtly non-lobulocentric / (pseudo) infiltrative into fat or stroma
    • Conspicuous myoepithelial cells with attenuated epithelial cells can appear like stands of single cells and mimic invasive lobular carcinoma
    • Atypical apocrine metaplasia: nuclear atypia / rare mitosis (Mod Pathol 1991;4:1)
    • (Pseudo) perineural invasion
Microscopic (histologic) images

Contributed by Julie M. Jorns, M.D.
Lobule with distortion Lobule with distortion Lobule with distortion

Lobule with distortion

Calcifications and drag

Calcifications and drag

Drag mark

Drag mark


Calponin

Calponin

p63

p63

Sclerosing adenosis with DCIS Sclerosing adenosis with DCIS Sclerosing adenosis with DCIS

Sclerosing adenosis with DCIS


Sclerosing adenosis with DCIS Sclerosing adenosis with DCIS

Sclerosing adenosis with DCIS

Cytology description
Positive stains
Videos

Pathology mini tutorial

Sample pathology report
  • Left breast, core biopsy:
    • Fibrocystic changes including sclerosing adenosis with microcalcifications
Differential diagnosis
  • Microglandular adenosis:
    • Haphazardly distributed glands (lacks lobulocentric pattern)
    • Lacks myoepithelium but has intact basement membrane
  • Tubular adenoma:
    • Well circumscribed
    • Nodular growth may mimic nodular adenosis / adenosis tumor
    • Uniform, closely packed tubules (lacks significant distortion by fibrosis)
  • Invasive carcinoma:
    • May be difficult to morphologically distinguish from florid sclerosing adenosis with marked distortion and/or involvement by atypia or DCIS
    • Displays desmoplastic stromal response
    • Lacks myoepithelium
  • Invasive tubular carcinoma:
    • More widely spaced tubules with single epithelial layer
    • Displays desmoplastic stromal response
Board review style question #1

A premenopausal woman underwent breast biopsy for screening detected microcalcifications showing the pictured lesion. This lesion typically is associated with

  1. Abundant cytologic atypia
  2. Clinically palpable mass
  3. Lack of myoepithelium
  4. Variable imaging features
Board review style answer #1
D. Variable imaging features

The pictured lesion is sclerosing adenosis, a benign breast lesion characterized by expansion of glands (with preserved 2 cell layers: inner epithelial and outer myoepithelial cells) within the terminal duct lobular unit with distortion by fibrosis / sclerosis. Most of the time, sclerosing adenosis lacks cytologic atypia. Sclerosing adenosis frequently has calcifications due to entrapped secretions. However, when abundant, sclerosing adenosis may present as a distortion or mass on imaging. Sometimes sclerosing adenosis clinically presents as a palpable mass, as with nodular adenosis / adenosis tumor. However, sclerosing adenosis can often be an incidental finding when there is another indication for biopsy. Thus, imaging findings are variable, depending on size and extent of the lesion.

Comment Here

Reference: Sclerosing adenosis
Board review style question #2

Sclerosing adenosis of the breast (without atypia) imparts what risk for future breast cancer?

  1. No increased risk
  2. 1.5 - 2x increased risk
  3. 4 - 5x increased risk
  4. 8 - 10x increased risk bilaterally
  5. 8 - 10x increased risk ipsilaterally
Board review style answer #2
B. 1.5 - 2x increased risk

Sclerosing adenosis is considered part of the spectrum of proliferative fibrocystic changes, which imparts a 1.5 - 2x increased risk for future breast cancer. This is opposed to nonproliferative fibrocystic change which has no increased risk and atypical ductal hyperplasia (ADH) with 4 - 5x, ductal carcinoma in situ (DCIS) with 8 - 10x (unilateral: ipsilateral side) and lobular carcinoma in situ (LCIS) with 8 - 10x (bilateral) increased risk for breast cancer.

Comment Here

Reference: Sclerosing adenosis
Back to top
Image 01 Image 02