Last edited 09/2019 and last reviewed 01/2022

Gynaecomastia can be defined as the benign proliferation of male breast glandular tissue (1) with a mass consisting of >2cm in size, which appears as firm, palpable, subareolar gland and ductal breast tissue on examination (2)

  • this condition mainly results from a relative decrease in androgen effect or increase in oestrogen effect (2)
  • it may be drug-induced or associated with conditions which alter the oestradiol / testosterone ratio, for example, chronic liver disease
  • it commonly occurs in puberty and old age and is most often entirely reversible.

Pseudogynaecomastia is the condition in which breast enlargement occurs mainly due to excess adipose tissue formation (2).

Male breast cancer accounts for about 0.6% of all breast cancer: there almost 400 cases annually in the UK (c.f. 55,000 in women) (3).