Gynaecomastia is a condition of benign hyperplasia of the breast tissue in men and should be distinguished from simple adiposity. Gynaecomastia develops as a result of a relative excess of oestrogens over testosterone, either because of increased production or action of oestrogens, or reduced production or action of androgens (Figures 29.1 and 29.2).
• Physiological Most commonly in the newborn or pubertal period. Around 50% of pubertal boys will have gynaecomastia at some stage, but this is usually self-limiting.
• Drugs A common cause, whether prescribed or taken recreationally. Examples include anti-androgens (e.g. spironolactone), oestrogens, testosterone (stimulates aromatase), cannabis and opiates.
• Hypogonadism (Chapter 28).
• Tumours Oestrogen or androgen-producing testicular or adrenal tumours. HCG-producing tumours, usually testicular but occasionally ectopic (e.g. lung).
• Systemic illness Classically, liver cirrhosis (increased oestrogen and lower bioavailability of androgens due to high levels of SHBG) but also chronic renal failure.
• Other conditions including obesity, thyrotoxicosis and androgen insensitivity.
Many cases are idiopathic with no clear underlying cause.
The history should elicit the duration and progression of gynaecomastia; recent and rapid onset should lead to clinical suspicion of a tumour. Symptoms and signs of hypogonadism (Chapter 28) and systemic disease (endocrine, hepatic or renal) should be sought in addition to a careful drug history. The breasts should be examined to confirm the presence of gynaecomastia and to document its extent. The testes must be palpated to exclude a tumour and to assess size (androgenic steroid abuse may, for example, lead to atrophy). Baseline blood tests should include measurement of 09.00 testosterone, oestradiol, LH and FSH, SHBG, HCG and LFTs. Depending on results, other tests may subsequently be required (e.g. tests for hypogonadism; Chapter 28, testicular ultrasound and chest X-ray if raised HCG, and abdominal CT or MRI if markedly raised oestradiol).
If an underlying disorder is identified this should be treated and offending drugs should be stopped if possible. Physiological gynaecomastia is usually self-limiting and does not generally require treatment. In persistent cases where there is significant cosmetic concern, medical treatment with antioestrogens (e.g. tamoxifen) can be tried, although success is variable and surgery is usually preferred.