The Basics - Gynaecomastia

Being aware of the potential causes will assist with appropriate history taking and examination, says Dr Kamilla Porter.

Gynaecomastia can occur at any age and can be physiological or pathological
Gynaecomastia can occur at any age and can be physiological or pathological

Gynaecomastia is defined as the benign enlargement of male breast tissue, where firm subareolar gland and ductal tissue will be palpable on examination, as opposed to breast enlargement caused by excess adipose tissue which is referred to as pseudogynaecomastia.

Gynaecomastia is common, with an incidence of more than 30%. It can occur at any age and may be physiological or pathological (see box below).

Causes of gynaecomastia


  • Neonates.
  • Puberty.
  • Ageing.
  • Obesity.


  • Drugs, including estrogens, digoxin, antipsychotics, finasteride, spironolactone, cimetidine, PPIs, anabolic steroids, antiretrovirals and hormonal therapies for prostate cancer.
  • Chronic liver disease.
  • Chronic kidney disease.
  • Pituitary disease.
  • Primary hypogonadism (viral orchitis, trauma and congenital absence of testes).
  • Testicular cancer.
  • Lymphoma.
  • Metastatic liver or bronchial cancers.
  • Hyperthyroidism.
  • Starvation and re-feeding.
  • Spinal cord injury.
  • Idiopathic.
  • Klinefelter’s (XXY) syndrome.
  • Hermaphroditism.
  • Testicular feminisation.

1 Physiological gynaecomastia
Prominent breast tissue in newborn males is extremely common, resulting from transfer of maternal estrogens, and can last several weeks. 60% of boys up to the age of 14 have gynaecomastia which may affect one breast more than the other; by age 20, prevalence is 19%.1

Gynaecomastia is more common in men aged over 50 due to the general decline in testosterone levels as well as a tendency towards weight gain in later life. In overweight men breast tissue is stimulated by excess estrogen resulting from the conversion of testosterone to estradiol by the enzyme aromatase found in adipose tissue.

2 Pathological gynaecomastia
Any condition or medication associated with low levels of testosterone (whether true reduction or due to high SHBG levels), significant conversion of testosterone to estrogen, or raised estrogen levels can result in gynaecomastia.

3 Symptoms and signs
Being aware of the causes of gynaecomastia will assist with appropriate history taking and examination. It is important to ascertain the duration and course of symptoms, and note a history of sexual dysfunction as well as medications and any recreational drugs, especially alcohol (as a risk factor for cirrhosis) and anabolic steroids.  

Consider the latter cause in a young man whose family report changes in behaviour and character. A rapid enlargement of breast tissue without any causative drugs would raise the suspicion of a hormone secreting tumour.

Gynaecomastia is often asymptomatic but occasionally men complain of irritation and some chaffing of the breast and less commonly of tenderness.

Ideally breast examination should be done with the patient supine. Thumb and forefinger should be placed over the outer and inner breast margins and brought together in a pinching movement. This will result in a disc of breast tissue under the nipple and areola area. A diameter of under 2cm is considered within normal limits, above 2cm is consistent with the definition of gynaecomastia.

A general physical examination should also be undertaken to look for signs of hyperthyroidism, chronic liver disease and hypogonadism, and include measurement of body mass index. Testicular examination should be done to assess size, as small testicles will suggest hypogonadism and also to check for masses or abnormal consistency suggestive of testicular cancer.

Gynaecomastia is usually bilateral and though around 10% of cases can involve just one breast always consider the possibility of breast cancer in a unilateral presentation. If an unusual mass, distorted nipple or areola, skin abnormality or axillary lymphadenopathy are found the patient should be referred urgently to the breast cancer clinic.

4 Investigations
Further investigation will depend on history and examination findings. Gynaecomastia is often an incidental finding on examination, particularly in overweight older patients and in general such patients do not require further evaluation.2

Blood tests are not necessary in pubertal boys or in men on medications associated with gynaecomastia. However, if the underlying cause is not obvious appropriate baseline blood tests would include TFT, U&Es and LFTs. If these are normal consider a hormone blood screen, which may include testosterone, LH, FSH, estradiol, beta-hCG, alpha-fetoprotein, estradiol, SHBG, prolactin and dehydroepiandrosterone (DHEA); see table below for an interpretation of results.

Interpreting hormone tests
Hormone test result Possible diagnoses
All normal Idiopathic gynaecomastia
Low testosterone with elevated LH Primary hypogonadism; Klinefelter’s syndrome
Low testosterone with normal LH Pituitary/hypothalamic disease
Elevated testosterone with elevated estradiol Androgen exposure; testicular tumour
Elevated estradiol with elevated SHBG Estrogen exposure; testicular/adrenal tumour
Elevated DHEA Adrenal tumour
Elevated beta-hCG Testicular/ectopic tumour
Elevated prolactin Pituitary tumour; drug related cause

Mammography is not required unless cancerous changes are suspected. Breast ultrasound may be undertaken if surgery is planned, to distinguish adipose tissue from gynaecomastia.

If there is testicular pain or a mass, testicular ultrasound is indicated and chest X-ray should be performed if lung cancer is suspected.

Depending on the hormonal profile, chromosomal karyotyping may be carried out. A hard irregular breast mass, nipple discharge, skin abnormality or chest wall mass all warrant a core biopsy.

5 Management
If the underlying cause is still not clear after primary care investigations, consider referring the patient to the local breast clinic. A quarter of cases turn out to be idiopathic.

In drug induced gynaecomastia the offending agent should be withdrawn. Where an underlying disorder has been identified, treating the condition should result in resolution of gynaecomastia, especially if onset is recent.

In patients with physiological gynaecomastia, especially adolescent boys, reassurance can be given that most cases are transitory, with more than 90% resolving by three years. For those who remain distressed by their symptoms despite reassurance, tamoxifen 10mg daily for six months may be of benefit. However, it is important to inform patients that this is an unlicensed use. 

The impact of gynaecomastia on a patient’s social and personal life should not be underestimated. Most regions now have stringent local guidelines limiting cosmetic procedures on the NHS but where a patient suffers significant pain or profound psychological distress surgical removal of breast tissue may be undertaken.

This may involve liposuction or subcutaneous mastectomy. The risks of surgery include haematoma, infection, scarring, sensory changes, breast asymmetry and a poor cosmetic result.

  • Dr Porter is a GP in Rochford, Essex


  •; this US website has medical information for patients, photos of gynaecomastia, and patient forums and blogs.

1. Niewoehner CB, Schorer AE. Gynaecomastia and breast cancer in men. BMJ 2008; 336: 709-13.

2. Best Practice: gynaecomastia.; last updated Sept 2011.

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