Gynaecomastia is a benign condition in which males develop breast tissue due to an imbalance between oestrogen and androgen activity. It is a common occurrence, affecting up to one third of men at some point in their lives. In many cases, gynaecomastia resolves spontaneously, even when the underlying cause remains unidentified. Despite its benign nature, the condition can lead to significant psychological distress, including embarrassment and anxiety, including the possibility of an underlying malignancy. However, male breast cancer is rare, with a prevalence of only 0.5–1%. By Nephron [CC BY-SA 3.0], via Wikimedia Commons Figure 1Hyperplasia of the breast tissue, as seen in as a case of gynaecomastia Pathophysiology Physiological gynaecomastia most commonly arises during adolescence, due to a temporary imbalance in hormone levels—specifically, a delayed surge in testosterone relative to oestrogen during puberty. Less frequently, it occurs in older men as a result of age-related declines in testosterone production. In contrast, pathological gynaecomastia stems from sustained alterations in the oestrogen:androgen ratio. This imbalance may be driven by a range of underlying mechanisms: Lack of testosterone Causes include Klinefelter’s syndrome, androgen insensitivity, testicular atrophy, or renal disease Increased oestrogen levels Causes include liver disease, hyperthyroidism, obesity, adrenal tumours, or certain testicular tumours (e.g. Leydig’s cell tumours) Medication* Common causative agents include digoxin, metronidazole, spironolactone, chemotherapy, goserelin, antipsychotics, or anabolic steroids Idiopathic *25% of all cases, either through an increased oestrogen activity or reduced testosterone activity Clinical Features Gynaecomastia typically develops gradually and may go unnoticed in its early stages. During clinical assessment, it is important to inquire about associated symptoms and any relevant co-morbidities. A thorough evaluation should include screening for any potential underlying cause, including the possibility of malignancy*. On examination, gynaecomastia usually presents as a rubbery or firm mass >2 cm in diameter. This mass originates beneath the nipple and extends outward across the breast tissue. Careful inspection and palpation are essential to rule out features suggestive of breast cancer. *A testicular examination is essential, especially in young patient presenting with the condition By Dr. Mordcai Blau [CC BY-SA 3.0], via Wikimedia Commons Figure 2The enlarged breast tissue, as seen in a case of gynaecomastia Differential Diagnosis The primary differential diagnosis for gynaecomastia is pseudogynaecomastia, which refers to the presence of adipose tissue in the breast region, typically associated with being overweight* *This can usually be tested on examination by pinching to see if there is an obvious disc of breast tissue present however if not palpable then further imaging and / or histology may be required to definitively exclude Investigations Diagnostic testing for gynaecomastia is generally reserved for cases where the underlying cause is unclear. If there is concern for malignancy, patients should undergo a triple assessment, which includes clinical examination, imaging (typically ultrasound or mammography), and tissue biopsy if indicated. When the cause remains unidentified, initial investigations should focus on liver and renal function tests. If these results are normal, a hormonal profile should then be conducted to evaluate for endocrine abnormalities contributing to the condition. Management Management of gynaecomastia is guided by the underlying cause and the stage of the condition. If a reversible factor is identified, such as medication use or hormonal imbalance, addressing this often leads to resolution of the condition. In many cases, simple reassurance is sufficient, particularly when the condition is mild, asymptomatic, or self-limiting. For patients experiencing discomfort or tenderness, medical therapy with Tamoxifen, a selective oestrogen receptor modulator, may help alleviate symptoms. Surgical intervention is rarely required and is typically reserved for select cases, mainly those with persistent, symptomatic gynaecomastia that does not respond to medical treatment. Key Points Pathological gynaecomastia occurs from changes in the oestrogen:androgen activity ratio It will present as a rubbery or firm mass, starting from underneath the nipple and spreading outwards over the breast region Tests are only necessary if the cause for gynaecomastia is uncertain; any suspicion of malignancy requires the triple assessment Do you think you’re ready? Take the quiz below Pro Feature - Quiz Gynaecomastia Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 Keep your streak going Unlock the full question bank You’ve made a great start. Continue with over 1,200 MRCS-style MCQs, two full mock papers, and ad-free revision with TeachMeSurgery Pro. Continue with Pro Rate This Article