Gynaecomastia refers to a benign excess of the male breast tissue, that is usually reversible. It is not a risk factor per se for developing male breast cancer.

Epidemiology

While it can occur at any age, it tends to have greater prevalence in two groups: adolescent boys and older men (some publications describe a trimodal age distribution, occurring in neonatal, pubertal, and elderly males ⁸). Prevalence of "asymptomatic" gynaecomastia ranges around ⁸:

• neonates: 60-90%

• adolescents: 50-60%

• men aged 50 to 69 years: up to 70%

Prevalence of "symptomatic" cases is markedly lower.

Clinical presentation 

Palpation usually demonstrates a palpable, tender, firm, mobile, disc-like mound of tissue ⁸.

Pathology

In gynaecomastia, there is enlargement of the male breast due to benign ductal and stromal proliferation. A hallmark of gynaecomastia is its central location under the nipple. Gynaecomastia in most cases tends to be unilateral and/or asymmetrical ³.

The imbalance between oestrogen action relative to androgen action at the breast tissue level appears to be a key aetiological factor in gynaecomastia ⁸.

Aetiology

The causes of gynaecomastia are many and include:

• hormonal

  • neonatal: maternal oestrogens

  • pubertal: high oestradiol levels

  • elderly: decline in testosterone levels

  • hypogonadism/androgen deficiency states:

    • Klinefelter syndrome

    • anorchism

    • testicular failure, e.g. testicular cancer

• drugs

  • diethylstilboestrol

  • spironolactone

  • thiazide diuretics

  • digoxin

  • anabolic steroids

  • oestrogen treatment

  • flutamide

  • finasteride

  • isoniazid

  • ergotamine

  • narcotics:

    • marijuana

    • heroin

  • cimetidine

  • nifedipine

  • reserpine

  • efavirenz

  • methyldopa

  • theophylline

  • valproic acid

• systemic disorders

  • advanced alcoholic cirrhosis

  • chronic pulmonary disease, e.g. emphysema, tuberculosis

  • haemodialysis in chronic renal failure

  • hyperthyroidism

  • malnutrition

• tumours: particularly oestrogenic tumours

  • adrenal carcinoma

  • hepatoma

  • lung cancer

  • pituitary adenoma

  • testicular cancer: including sex-cord stromal, and germ cell tumours ⁹

• idiopathic

Microscopic appearance

There can be three histological forms:

• florid

• intermediate

• fibrotic

Radiographic features

Mammography

May appear as an increased sub-areolar density, which may be flame-shaped.

Three mammographic patterns of gynaecomastia have been described representing various degrees and stages of ductal and stromal proliferation. They are ¹⁴:

• nodular pattern

• dendritic pattern

• diffuse glandular pattern

Early nodular gynaecomastia (florid phase) is seen in patients with gynaecomastia for less than 1 year. At mammography, there is often a nodular subareolar density.

Chronic dendritic gynaecomastia (quiescent phase) is seen in patients with gynaecomastia for longer than 1 year. Fibrosis becomes the dominant process and is irreversible. Mammograms this phase typically show a dendritic subareolar density with posterior linear projections radiating into the surrounding tissue toward the upper-outer quadrant.

Diffuse glandular gynaecomastia is commonly seen in patients receiving exogenous oestrogen. At mammography, there is enlargement of the breast and diffuse density with both dendritic and nodular features.

Ultrasound

Focal gynaecomastia can variably appear as a retroareolar, triangular, hypoechoic (~80% ²) mass.

In early nodular gynaecomastia, there can be subareolar fan or disc-shaped hypoechoic nodule surrounded by normal fatty tissue.

In diffuse glandular gynaecomastia, both nodular and dendritic features are seen surrounded by diffuse hyperechoic fibrous breast tissue.

In chronic dendritic gynaecomastia, there is often a subareolar hypoechoic lesion with an anechoic star-shaped posterior border, which can be described as fingerlike projections or "spider legs" insinuating into the surrounding echogenic fibrous breast tissue.

Differential diagnosis

• pseudogynaecomastia: involves breast enlargement (usually bilateral) caused by an excess of adipose tissue, which is not necessarily associated with constitutional obesity

• male breast cancer ¹²:

  • unilateral fixed painless irregular hard mass

  • may occur remotely from the areola (gynaecomastia does not)

  • skin thickening and tethering

See also

• male breast disease