Other nonneoplastic

Topic Completed: 1 November 2017

Minor changes: 17 May 2021

Copyright: 2002-2019,, Inc.

PubMed Search: Gynecomastia[TI] male[TI]

Carlos C. Diez Freire, M.D.
Shahla Masood, M.D.
Page views in 2020: 12,796
Page views in 2021 to date: 7,577
Cite this page: Diez Freire CC, Masood S. Gynecomastia. website. Accessed June 12th, 2021.
Definition / general
  • Enlargement of the male breast with a palpable mass that can be tender in the initial stages
  • Nipple and areola are enlarged in a minority of patients
Essential features
  • Epithelial hyperplasia and stromal edema or fibrous tissue with atrophic glands, depending on the type of gynecomastia
ICD coding
  • Common in newborns and infants
  • Typically seen in boys around puberty and adults over age 50
  • Can be unilateral or bilateral
    • Tends to be bilateral and symmetric in puberty and disappears by adulthood
  • Can be localized or generalized
  • Most cases are idiopathic or physiologic
  • In newborns and infants, gynecomastia is due to in utero exposure to estrogen and tends to resolve spontaneously
  • Other conditions associated with gynecomastia include:
    • Systemic disorders (hyperthyroidism, hypogonadism, cirrhosis, chronic renal failure and chronic pulmonary disease)
    • Hormone use (such as estrogen, androgens) and many drugs (digitalis, cimetidine, spironolactone, tricyclic antidepressants and marijuana)
    • Pulmonary carcinoma and germ cell tumors can cause gynecomastia via paraneoplastic hormone production
    • Decreased zinc levels have been postulated as a probable cause of gynecomastia in puberty but further studies need to be done to support this theory (J Trace Elem Med Biol 2017;44:274)
Clinical features
  • Most common male breast lesion
  • Can be unilateral (more commonly the left breast with a mass-like appearance) or bilateral (synchronous or asynchronous, more of a diffuse process)
  • Pendulous breast with a palpable soft nodule (subareolar or rarely peripheral); may be tender; typically 2 - 5 cm but may be up to 10 cm
  • Hyperplastic changes in breast epithelium and stromal changes are necessary for the diagnosis
Radiology description
  • There are two mammographic patterns associated with gynecomastia:
    • Dendritic configuration (retroareolar with radial extensions)
    • Triangular configuration (recent onset disease)
Case reports
Prognosis and treatment
  • May recur if the underlying cause is not addressed
  • No strong evidence of increased risk of breast carcinoma
  • In most cases, no specific treatment is required; treatment of the underlying cause can resolve the issue
    • Antiestrogen therapy has been used (tamoxifen, danazol)
    • Surgery (liposuction or skin sparing, nipple sparing mastectomy) is an option
Clinical images

Contributed by Carlos C. Diez Freire, M.D.

Subareolar "disk-like" enlargement

Images hosted on other servers:

Spironolactone induced

Gross description
  • Soft, rubbery, firm subareolar mass
  • Gray / white, ill defined cut surface
Microscopic (histologic) description
  • Three phases of proliferative changes have been described:
    • Florid gynecomastia is characterized by ductal epithelial hyperplasia with flat or papillary patterns and increased periductal stromal cellularity, prominent vascularity and edema; these changes occur within 1 year of onset
    • Intermediate gynecomastia is characterized by a florid component and increased fibrosis; it can last up to 6 months and represents a transitional phase in the maturation of the lesion
    • Fibrous phase is characterized by less epithelial proliferation and more collagenous stroma with less edema and vascularity; it occurs after the lesion has been present for 12 or more months
  • Other findings include pseudoangiomatous hyperplasia (PASH), lobule formation with pseudolactational hyperplasia and apocrine and squamous metaplasia
  • Cytologic atypia in the form of atypical ductal hyperplasia with mitosis can be present and has also been related to flutamide therapy (Arch Pathol Lab Med 2000;124:625) for prostate cancer and alopecia
Microscopic (histologic) images

Contributed by Carlos C. Diez Freire, M.D.

Cellular stroma and periductal edema

Epithelial proliferation, cellular stroma and periductal edema

Florid type gynecomastia

Fibrous type gynecomastia

Pseudolactational hyperplasia in this area

Epithelial proliferation

Collagenized stroma

AFIP images

Periductal stromal
edema with
mild epithelial

Solid form with
microlumina, different
cell types in central
and peripheral duct

Post estrogen treatment for prostatic carcinoma

With atypical duct hyperplasia

Micropapillary pattern
of slender strands of
cells with hyperchromatic

Contributed by Alberto M. Locante, M.D.

Left breast mass in a 74 year old man

Images hosted on other servers:


Cytology description
  • Cytologic features are reminiscent of fibroadenoma
  • Fine needle aspiration (FNA) yields a moderately cellular smear composed of epithelial and stromal fragments in a background of naked bipolar to oval myoepithelial nuclei
  • Epithelial fragments are large, monolayered, cohesive sheets with some nuclear overlapping and indistinct cell borders
Cytology images

Images hosted on other servers:

Clusters of bland, cohesive epithelial cells

Positive stains
  • ER, PR and AR (epithelial cells), p63, CK5 and CK14 (myoepithelial cells)
  • PSA is positive in hyperplastic and nonhyperplastic ductal epithelium
Negative stains
Electron microscopy description
  • Electron microscopy (EM) confirms the proliferation of myoepithelial and epithelial cells, fibroblasts and myofibroblasts in the stroma
  • Ultrastructural features are similar to those encountered in usual ductal hyperplasia of the female breast
Board review style question #1
Which of the following is the most common etiology in the development of gynecomastia?

  1. Cirrhosis
  2. Drugs
  3. Estrogen exposure in utero
  4. Idiopathic or physiologic
  5. Hyperthyroidism
Board review style answer #1
D. Idiopathic or physiologic

Comment here

Reference: Gynecomastia
Back to top
Image 01 Image 02