Other nonneoplastic


Editorial Board Member: Julie M. Jorns, M.D.
Deputy Editor-in-Chief: Gary Tozbikian, M.D.
Elaine Zhong, M.D.
Hannah Y. Wen, M.D., Ph.D.

Last author update: 13 August 2021
Last staff update: 31 May 2022

Copyright: 2002-2024,, Inc.

PubMed Search: Gynecomastia[TI] breast[TI] free full text[sb]

Elaine Zhong, M.D.
Hannah Y. Wen, M.D., Ph.D.
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Cite this page: Zhong E, Wen HY. Gynecomastia. website. Accessed February 23rd, 2024.
Definition / general
  • Benign enlargement of the male breast, typically presenting as a palpable subareolar mass
  • Histologically identical gynecomastoid hyperplasia can be seen in female breast
Essential features
  • Benign ductal and stromal proliferation with characteristic stromal cuffing, typically with 3 layered ductal lining and pseudoangiomatous stromal hyperplasia
ICD coding
  • ICD-10: N62 - hypertrophy of breast
  • ICD-11: GB22 - hypertrophy of breast
  • Trimodal age distribution:
    • Infancy and neonatal period
    • Puberty (peak incidence age 13 - 14)
    • Older males age 50 - 80 (likely due to increased adiposity, decreased testosterone, medications)
  • Estimated lifetime prevalence of 32 - 65% of men, depending on method of assessment (Indian J Endocrinol Metab 2014;18:150)
Clinical features
  • Histologic changes are necessary for the diagnosis; important to exclude malignancy
  • Usually not needed, except to identify underlying causes
    • Estrogen to testosterone ratio (E2/TTE), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, thyroid stimulating hormone (TSH), hCG, AFP, dehydroepiandrosterone (DHEA), cortisol, karyotyping
Radiology description
  • 3 patterns of mammographic findings (Radiographics 1999;19:559, Andrology 2021 May 25 [Epub ahead of print])
    • Nodular: 72%, corresponds to florid histologic phase; fan shape radiating from nipple into surrounding fat
    • Dendritic: 18%, corresponds to fibrous histologic phase; flame shaped opacity with radiating projections penetrate surrounding fat / upper outer quadrant
    • Diffuse: ~10%, typically in transgender females undergoing gender affirming hormonal therapy; resembles dense female breast but heterogeneous and without Cooper ligaments
  • Imaging useful to exclude pseudogynecomastia and carcinoma
Radiology images

Contributed by Elaine Zhong, M.D.
Mammogram Mammogram


Prognostic factors
  • May recur if underlying cause is not addressed
  • No strong evidence of increased risk of breast carcinoma
Case reports
  • Some regress spontaneously within 2 years and do not require treatment
  • Sudden or symptomatic gynecomastia may be treated medically
  • Identify and treat any underlying causes
  • Excision in adult patients to rule out malignancy and for cosmesis; however, recurrence is common if the underlying cause is not identified and treated
Clinical images

Images hosted on other servers:

Physiologic gynecomastia in puberty

Spironolactone induced

Gross description
  • Soft, rubbery to firm gray-white subareolar mass
  • Can be ill defined subareolar induration
Microscopic (histologic) description
  • Increased number of ducts with characteristic 3 layer epithelium (Am J Surg Pathol 2012;36:762):
    • Luminal epithelium expressing CK5/6, CK14
    • Intermediate cuboidal to columnar epithelium expressing ER, PR, AR
    • Outer myoepithelium expressing CK5/6 and CK14
  • 3 patterns of proliferative changes, without correlation to age or duration of lesion (Am J Clin Pathol 1972;57:431, J Plast Surg Hand Surg 2018;52:166)
    • Florid: irregular branching ducts, mild to moderate epithelial hyperplasia, cellular / myxoid / edematous stroma cuffing around ducts; can have papillary or cribriform architecture, myoepithelial hyperplasia
    • Intermediate: mixture of florid and fibrous patterns
    • Fibrous: quiescent epithelium, hyalinized hypocellular stroma
  • Other findings can include pseudoangiomatous stromal hyperplasia (PASH), apocrine or squamous metaplasia
  • Atypical ductal hyperplasia (ADH) in 0.4 - 5.4% (Ann Plast Surg 2015;74:163, Histopathology 2015;66:398)
Microscopic (histologic) images

Contributed by Elaine Zhong, M.D.
Florid pattern Florid pattern Florid pattern Florid pattern

Florid pattern

3 layer epithelium

3 layer epithelium

Fibrous pattern Fibrous pattern

Fibrous pattern

ADH in gynecomastia

ADH in gynecomastia

DCIS in gynecomastia

DCIS in gynecomastia

Virtual slides

Images hosted on other servers:

Excision from 33 year old man

Biopsy from 81 year old man

Cytology description
  • Biphasic epithelial and stromal fragments in a background of scattered single bipolar nuclei, similar to fibroadenoma
  • Spindle cells, apocrine cells, foamy macrophages can be present
Cytology images

Images hosted on other servers:

Clusters of bland, cohesive epithelial cells

Positive stains
Sample pathology report
  • Breast, retroareolar; core biopsy:
    • Gynecomastia, (florid, intermediate or fibrotic) stage.
Differential diagnosis
  • Male breast cancer:
    • Histology identical to carcinoma of the female breast
  • Atypical ductal hyperplasia:
    • Monomorphic intraductal cells in rigid cribriform, micropapillary or solid formations
  • Myofibroblastoma:
    • Mass forming spindle cell proliferation that may entrap normal glandular elements
    • Variable morphology and cellularity
  • Mammary hamartoma:
    • Circumscribed mass
    • Additional mesenchymal elements (smooth muscle, adipose tissue, cartilage, etc.) may be present
  • Fibroadenoma:
    • Circumscribed mass
    • Uniform stroma without significant periductal cuffing
    • Intracanalicular or pericanalicular pattern of glandular elements
Board review style question #1
Which of the following is the most common etiology in the development of gynecomastia?

  1. Cirrhosis
  2. Estrogen exposure in utero
  3. Hyperthyroidism
  4. Idiopathic
  5. Klinefelter syndrome
Board review style answer #1
D. Idiopathic

Comment here

Reference: Gynecomastia
Board review style question #2

What is the immunohistochemical profile of the intermediate epithelial cells of gynecomastia?

  1. ER/PR/AR+, CK5/6+
  2. ER/PR/AR+, CK5/6-
  3. ER/PR/AR-, CK5/6+
  4. ER/PR/AR-, CK5/6-
Board review style answer #2
B. ER/PR/AR+, CK5/6-

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Reference: Gynecomastia
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