The one-line answer

Gynaecomastia is benign glandular proliferation driven by oestrogen excess relative to androgen at the breast; pubertal disease is common and regresses with reassurance; adult-onset disease carries a detectable, often treatable cause in 43% and earns a genital examination with testicular ultrasound plus a hormone panel; drugs cause 10 to 25%; imaging is selective with mammographic nodular, dendritic and diffuse patterns and ultrasound disks that fibrose; painful recent disease may respond to a short tamoxifen course; long-standing disease is surgical with liposuction plus adenectomy; and gynaecomastia itself is not premalignant. The surgeon's error is never missing rarity; it is imaging the obvious, biopsying the physiological, and reassuring the adult without examining the testes.^[1]^[2]^[7]^[11]

A 16-year-old boy with tender bilateral subareolar ridges and a 58-year-old man with a new unilateral firm lump walk the whole topic in one clinic: reassure the boy whose disease is transient, hunt the cause with genital examination and labs in the man, image only the equivocal, biopsy the suspicious directly, and keep surgery for the long-standing case that never regressed.^[1]^[3]^[4]

Definition — gland, not fat, with a ridge you can feel

Gynecomastia (GM) is a benign proliferation of the glandular tissue of the breast in men — gland is the diagnosis, fat alone is not.^[1]
Gynecomastia (GM) is characterized by enlargement of the male breast, caused by glandular proliferation and fat deposition — most clinical cases mix both, but the gland defines the disease.^[2]
Clinically, gynecomastia is characterized by the presence of a firm or rubbery, discrete, subareolar ridge of glandular tissue that is symmetrical in shape, freely movable, and nonadherent to skin or underlying tissue — feel for the ridge before naming it.^[3]
GM is characterized by enlargement of the male breast due to the proliferation of glandular ducts and stromal components — ducts plus stroma is the tissue the pathologist sees.^[4]
The main purpose of evaluating a patient with GM is to establish the diagnosis and differentiate true GM from pseudogynecomastia, exclude breast cancer, and detect the possible cause — true versus pseudo versus cancer is the first triage.^[10]
Breast examination should confirm the presence of palpable glandular tissue to discriminate GM from lipomastia (pseudo-gynecomastia) and rule out the suspicion of malignant breast tumor — the examination, not the scan, makes the first cut.^[1]

Mechanism — oestrogen stimulation against androgen brake

A hormonal imbalance between estrogens and androgens is the key hallmark of GM generation — remember imbalance, not absolute excess alone.^[2]
Gynecomastia is caused by an imbalance between the stimulatory effect of estrogen and the inhibitory effect of androgen at the breast tissue level — stimulation unopposed is the unit mechanism.^[3]
The main cause of GM during adolescence is physiological or pubertal GM, which is primarily attributed to an imbalance between estrogen and androgen activity — puberty is the same mechanism at the wrong hour.^[4]
The etiology of GM is attributable to physiological factors, endocrine tumors or dysfunctions, non-endocrine diseases, drug use or idiopathic causes — physiology, hormones, systemic disease, drugs, or none found.^[2]
An underlying pathology may be revealed in 45%-50% of adult men with GM, such as aggravating medications, systemic diseases, obesity, endocrinopathies, or malignancy — adult disease earns the cause hunt.^[10]

Epidemiology — three peaks, common in normal men, rising fast

It is a common condition, which may occur physiologically and shows three age peaks during a male's lifespan: infancy, puberty, and senescence — expect it at both ends and in the middle.^[10]
Gynecomastia may occur physiologically in the neonatal period, during puberty, and in old age — the same three peaks in the paediatric lens.^[3]
It is a frequent condition with a reported prevalence of 32-65%, depending on the age and the criteria used for definition — definition changes the count.^[1]
The prevalence of palpable gynecomastia was determined in 306 normal adult men ranging in age from 17-58 yr — this is the normal-men denominator.^[5]
Palpable breast tissue was present in 36% and was bilateral in all but 7 subjects — common and usually bilateral in normal men.^[5]
In the great majority of cases, the gynecomastia was 4 cm or less in diameter — small is the norm.^[5]
A diameter greater than 5 cm was distinctly unusual — size above 5 cm breaks the normal pattern.^[5]
With advancing age there was a progressive increase in the prevalence of gynecomastia — age is the gradient.^[5]
In those over the age of 44, the prevalence was 57% — more than half of older normal men have palpable tissue.^[5]
Overall, a total 17 601 males (age 0-80 years) were registered with an incident diagnosis of gynecomastia within the 20-year study period, corresponding to 880 new cases per year and an average 20-year incidence of 3.4 per 10 000 men (age 0-80 years) — the national-registry denominator.^[6]
The average annual incidence was 6.5/10 000 in postpubertal males age 16 to 20 years and 4.6/10 000 in males age 61 to 80 years, with a respective 5- and 11-fold overall increase in these 2 age groups over the 20-year period — the rise concentrates at puberty and senescence.^[6]
Gynaecomastia affects half of the male population at some stage in their life — half is the lifetime frame for counselling.^[9]
Gynaecomastia is the most common benign condition of the male breast and accounts for up to 80% of male breast referrals — the breast clinic denominator.^[13]
Gynaecomastia was more prevalent in the under twenties age group — referrals skew young.^[13]

Adolescent disease — transient, stressful, reassurance first

GM of infancy and puberty are common, benign conditions resolving spontaneously in the majority of cases — infancy and puberty usually need nothing.^[1]
GM of puberty is a common condition, affecting approximately 50% of mid-pubertal boys; in more than 90% of cases, it resolves spontaneously within 24 months — quote the half and the 90% at 2 years.^[1]
Gynecomastia (GM) is a common and continuously evolving condition that commonly occurs during adolescence — evolving is the warning against one-visit certainty.^[4]
It is the source of significant embarrassment and psychological stress in adolescent males — name the distress before the boy does.^[4]
Physiological GM is typically transient and resolves within several months, although it may take several years to resolve — months usually, years sometimes.^[4]
Since most cases of physiological gynecomastia regress spontaneously with time, reassurance is all that is necessary — reassurance is the treatment.^[3]
GM may also be caused by other pathological conditions and could be indicative of an endocrine disease — persistence or atypia breaks the reassurance rule.^[4]
The challenge for the physician is to distinguish physiological gynecomastia from those with an underlying pathology — that distinction is the whole adolescent job.^[3]
Most men are looking for reassurance that their condition is benign and that no intervention is required — offer psychological support as part of treatment, not as an afterthought.^[13]

Adult workup — the 43% with treatable cause set the standard

Gynaecomastia is a benign proliferation of glandular tissue of the breast; however, it is an important clinical observation because it can be the first symptom of an underlying disease — the first symptom framing sets the workup threshold.^[7]
Thirty-two men who did not have gynaecomastia when examined were excluded; leaving 786 men for final analyses — the examined denominator behind the workup numbers.^[7]
They underwent an andrological examination, ultrasound of the testicles and analysis of endogenous serum hormones levels — examination plus testicular ultrasound plus hormones is the modelled workup.^[7]
In 43% of men with adult onset of gynaecomastia (≥18 years) an underlying, and often treatable, cause could be detected — adult onset earns the full hunt.^[7]
In men younger at onset an underlying cause for gynaecomastia could be detected in merely 7.7% — young onset rarely hides disease, adult onset commonly does.^[7]
GM of adulthood is more prevalent among the elderly and proper investigation may reveal an underlying pathology in 45-50% of cases — the guideline range matches the cohort.^[1]
The purpose of GM assessment should be the detection of underlying pathological conditions, reversible causes (administration/abuse of aggravating substances), and the discrimination from other breast lumps, particularly breast cancer — pathology, reversible cause, cancer discrimination.^[1]
The medical history should include information on the onset and duration of GM, sexual development and function, and administration or abuse of substances associated with GM — onset, puberty, sex, substances.^[1]
The physical examination should detect signs of under-virilization or systemic disease — look beyond the breast.^[1]
We recommend that the physical examination should include the examination of the genitalia to rule out the presence of a palpable testicular tumor and to detect testicular atrophy — genitalia are mandatory, not optional.^[1]
Assessment should comprise a thorough medical history and physical examination of the breast and genitalia (including testicular ultrasound) — palpation misses tumours that ultrasound finds.^[1]
A set of laboratory investigations may integrate the evaluation: testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicular stimulating hormone (FSH), thyroid stimulating hormone (TSH), prolactin, human chorionic gonadotropin (hCG), alpha-fetal protein (AFP), liver and renal function tests — the full panel when the workup is warranted.^[1]
For pathological gynecomastia, treatment should be directed at the underlying cause, if possible — cause first, breast second.^[3]
Clinical evaluation must address diagnostic confirmation, search for an etiological factor and classify GM into severity grades to guide the treatment — confirm, find, grade, then treat.^[2]

Drugs are estimated to cause about 10 - 25% of all cases of gynecomastia — ask the drug history in every adult.^[8]
Most of the reported drug-gynecomastia associations were based on poor quality evidence — believe the short definite list, hold the long list lightly.^[8]
The drugs definitely associated with the onset of gynecomastia are spironolactone, cimetidine, ketoconazole, hGH, estrogens, hCG, anti-androgens, GnRH analogs and 5-α reductase inhibitors — memorise this fence before stopping a drug.^[8]
Medications probably associated with gynecomastia include risperidone, verapamil, nifedipine, omeprazole, alkylating agents, HIV medications (efavirenz), anabolic steroids, alcohol and opioids — probable means review, not reflex cessation.^[8]
Watchful waiting is recommended after treatment of underlying pathology or discontinuation of substances associated with GM — stop the cause, then wait before operating.^[1]

Imaging — selective, patterned, and routinely overused

Most male breast lesions can be diagnosed on clinical grounds; however, in certain cases, when physical examination is inconclusive, imaging may be helpful — clinical first, imaging for the equivocal.^[10]
Breast imaging may be used whenever the clinical examination is equivocal — the guideline gives the same boundary.^[1]
In suspicious lesions, core needle biopsy should be sought directly instead — suspicious skips imaging as the decider and goes to needle.^[1]
GM is seen in mammography as a subareolar opacity and three mammographic patterns of GM are described: nodular, dendritic, and diffuse, corresponding to florid GM of early onset, fibrous persistent GM, and GM due to exogenous estrogen administration, respectively — nodular is florid early, dendritic is fibrous persistent, diffuse is exogenous oestrogen.^[10]
In ultrasound (US), florid GM is depicted as a disk-shaped, hypoechoic area underlying the areola, whereas echogenicity of the lesions increases as fibrosis develops — hypoechoic disk early, echogenic late.^[10]
Both mammography and US are sensitive and specific to diagnose GM and distinguish it from breast cancer — either modality separates gland from cancer when needed.^[10]
When clinical findings are suggestive of malignancy or imaging findings are inconclusive, a histological confirmation should be sought — inconclusive imaging ends in tissue.^[10]
A retrospective study assessing the imaging of the male breast in 557 patients over a 10-year period found the overuse pattern behind the discourage-routine rule.^[11]
The modalities used were mammography in 65%, ultrasound in 51% and both in 26% — this is how often surgeons currently image.^[11]
Most examinations, 519, were BI-RADS 1 or 2, and 38 were BI-RADS 3 or higher — almost all imaging was benign.^[11]
Malignancies were diagnosed in five patients (0.89%) — under 1% cancer in an imaged male-breast cohort.^[11]
Imaging had a sensitivity of 80% and a specificity of 99% — specific, not sensitive, in this mixed cohort.^[11]
The positive predictive value was 44% and the negative predictive value 99.8% — a negative scan reassures, a positive scan still needs tissue.^[11]
Imaging is not warranted unless there are suspicious abnormalities — the overuse conclusion in one line.^[11]
Routine imaging of gynecomastia should be discouraged — do not scan the obvious bilateral pubertal breast.^[11]
A total of 628 patients with 518 mammograms and 423 ultrasounds were reviewed in the mammography-versus-ultrasound cohort.^[12]
The final diagnoses were: 19 carcinomas, 526 gynaecomastias, 84 other benign conditions and 25 normal — gynaecomastia dominates, cancer is uncommon.^[12]
Mammography was the most sensitive (94.7%) and ultrasound the most specific (95.3%) for detection of malignancy — mammo finds, ultrasound excludes.^[12]
Mammography and ultrasound, with a negative predictive value close to 100%, make it possible to avoid very many unnecessary surgical procedures in men — a negative workup avoids the operation.^[12]

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Core biopsy (CB) became the histological investigation of choice for men with unilateral disease — unilateral gets tissue when indicated.^[13]
Two hundred seventy-one consecutive male patients (mean age, 57 years) with unilateral breast symptoms underwent bilateral mammography — the unilateral-symptom experiment.^[18]
Of 271 male patients, 29 were pathologically diagnosed with breast cancer. There was no bilateral breast cancer — cancer is ipsilateral only in this series.^[18]
The sensitivity, specificity, positive and negative predictive values, and accuracy were 96.6%, 96.7%, 77.8%, 99.6%, and 96.7%, respectively, for unilateral review — unilateral-plate numbers.^[18]
The diagnostic performance of unilateral mammography is comparable with bilateral mammography in male patients with unilateral breast symptoms — the second plate adds no accuracy.^[18]
Unilateral mammography also has the advantage of reducing radiation exposure — one plate when one breast complains.^[18]

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Weight loss, reassurance, pharmacotherapy with tamoxifen and surgical correction are the therapeutic options — the full ladder in one line.^[2]
Watchful waiting is recommended after treatment of underlying pathology or discontinuation of substances associated with GM — waiting is active management after the cause is fixed.^[1]
T treatment should be offered to men with proven T deficiency — replace testosterone only when deficiency is proven.^[1]
The use of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs) and non-aromatizable androgens is not justified in general — the guideline does not endorse routine hormonal manipulation.^[1]
If gynecomastia persists in spite of the above measures and treatment becomes necessary, tamoxifen is the treatment of choice — persistent disease that needs drugs gets tamoxifen first.^[3]
Men with painful gynaecomastia were given 10 mg of tamoxifen for 3 months — the studied painful-disease regimen.^[9]
Thirteen men (median age 36) were placed on tamoxifen — small, young, painful cohort.^[9]
Ten patients responded well to tamoxifen — most painful cases improved.^[9]
One patient developed calf tenderness and stopped the medication — tolerability is good with rare stoppage.^[9]
Tamoxifen appears safe and effective in men with painful idiopathic or physiological gynaecomastia and should be considered as an initial option before contemplating surgery — painful recent disease gets tamoxifen before knife.^[9]
Surgical treatment is the therapy of choice for patients with long-lasting GM — persistence is the surgical indication.^[1]
We suggest surgical treatment only for patients with long-lasting GM, which does not regress spontaneously or following medical therapy — long-lasting and non-regressing is the fence.^[1]
For long-standing GM, the best results are generally achieved through surgery, combining liposuction and mammary adenectomy — fat plus gland needs both tools.^[2]
Reduction mammoplasty may be considered for resistant cases — resistant disease ends in reduction.^[3]
There were 70 mastectomies performed on 52 subjects in the double-donut series — bilateral disease dominates the operative cohort.^[14]
The average age was 47 (23-73) years old — adult operative population.^[14]
The average total volume of breast tissue excised via the previous technique was 97.4 cm3, this increased to 186.5 cm3 with the new technique — the extended incision resects nearly twice the tissue.^[14]
No necrosis of the NAC was seen and no wound infections resulted in complication — nipple and wound safety in this series.^[14]
Cosmetic satisfaction was seen in 98% of patients — satisfaction is high with the mastopexy-skin-reduction approach.^[14]

Cancer boundary — gynaecomastia is not premalignant

Male breast cancer is rare; GM should not be considered a premalignant condition — say this to every worried patient.^[1]
Review of 932 males with breast pathology was performed to identify cases of ADH — the male-ADH denominator.^[15]
Nineteen males were diagnosed with ADH from June 2003 to September 2018 — ADH in men is uncommon.^[15]
Median patient age at ADH diagnosis was 25 years (range 18-72 years) — young men with gynaecomastia carry the ADH in this series.^[15]
At a mean follow-up of 75 months (range 4-185 months), no patient developed breast cancer — excised gynaecomastia with ADH shows no cancers at 6 years.^[15]
Occurrence of male breast cancer, a rare disease, peaks at age 71 years — old-age cancer against young-adult gynaecomastia.^[16]
Familial cases usually have BRCA2 rather than BRCA1 mutations — BRCA2 is the male-breast gene.^[16]
Hyperoestrogenisation resulting from Klinefelter's, gonadal dysfunction, obesity, or excess alcohol, all increase risk as does exposure to radiation, whereas gynaecomastia does not — shared oestrogenic risks raise cancer, gynaecomastia itself does not.^[16]
Presentation is usually a lump or nipple inversion, but is often late, with more than 40% of individuals having stage III or IV disease — late lumps, not gynaecomastia, are the cancer story.^[16]
Because 90% of tumours are oestrogen-receptor-positive, tamoxifen is standard adjuvant therapy — male cancer is tamoxifen-responsive, which is a different tamoxifen from the gynaecomastia course.^[16]
Male breast cancer (MBC) is rare, accounting for less than 1% of all breast cancer but the incidence has increased worldwide — rare but rising.^[17]
BRCA2 carriers have 80 times the risk of the general population — the number that changes counselling and referral.^[17]
Men generally present with breast cancer at an older age compared with women — older than the female counterpart.^[17]

Exam pearls and pitfalls — what fails the viva

Never offer routine imaging for clinically obvious bilateral gynaecomastia without suspicious features — 519 of 557 examinations were BI-RADS 1 or 2 and routine imaging is discouraged.^[11]
Never skip the genital examination and testicular ultrasound in adult-onset disease — detection of a testicular tumor by palpation has low sensitivity and the 43% cause rate punishes the skippers.^[1]^[7]
Never start SERMs, aromatase inhibitors or non-aromatizable androgens as routine gynaecomastia therapy — the guideline does not justify them in general, whatever the clinic habit.^[1]
Never operate the recent pubertal breast that would have regressed — more than 90% resolve within 24 months and reassurance is all that is necessary.^[1]^[3]
Never delay tissue when the picture is suspicious — core needle biopsy goes directly instead of another scan.^[1]
Say the mechanism in one breath at the station: stimulatory oestrogen unopposed by inhibitory androgen at the breast, with ducts and stroma proliferating — then name the bucket for this patient.^[2]^[3]^[4]

References18Show

[1]Kanakis GA, et al. EAA clinical practice guidelines-gynecomastia evaluation and management. Andrology, 2019.PMID 31099174
[2]Barros AC, et al. Gynecomastia: physiopathology, evaluation and treatment. Sao Paulo Med J, 2012.PMID 22790552
[3]Leung AKC, et al. Gynecomastia in Infants, Children, and Adolescents. Recent Pat Endocr Metab Immune Drug Discov, 2017.PMID 28260521
[4]Metwalley KA, et al. Gynecomastia in adolescent males: current understanding of its etiology, pathophysiology, diagnosis, and treatment. Ann Pediatr Endocrinol Metab, 2024.PMID 38712491
[5]Nuttall FQ, et al. Gynecomastia as a physical finding in normal men. J Clin Endocrinol Metab, 1979.PMID 429488
[6]Koch T, et al. Marked Increase in Incident Gynecomastia: A 20-Year National Registry Study, 1998 to 2017. J Clin Endocrinol Metab, 2020.PMID 32754750
[7]Mieritz MG, et al. Gynaecomastia in 786 adult men: clinical and biochemical findings. Eur J Endocrinol, 2017.PMID 28179453
[8]Deepinder F, et al. Drug-induced gynecomastia: an evidence-based review. Expert Opin Drug Saf, 2012.PMID 22862307
[9]Hanavadi S, et al. The role of tamoxifen in the management of gynaecomastia. Breast, 2006.PMID 15998589
[10]Billa E, et al. Imaging in gynecomastia. Andrology, 2021.PMID 34033252
[11]Lapid O, et al. Overuse of imaging the male breast-findings in 557 patients. Breast J, 2015.PMID 25772378
[12]Muñoz Carrasco R, et al. Mammography and ultrasound in the evaluation of male breast disease. Eur Radiol, 2010.PMID 20571799
[13]Al-Allak A, et al. Gynaecomastia: a decade of experience. Surgeon, 2011.PMID 21843819
[14]Wyrick DL, et al. Changing practices: The addition of a novel surgical approach to gynecomastia. Am J Surg, 2018.PMID 29395029
[15]Coopey SB, et al. Atypical ductal hyperplasia in men with gynecomastia: what is their breast cancer risk? Breast Cancer Res Treat, 2019.PMID 30666539
[16]Fentiman IS, et al. Male breast cancer. Lancet, 2006.PMID 16488803
[17]Fox S, et al. Male breast cancer: an update. Virchows Arch, 2022.PMID 34458944
[18]Yoon B, et al. Male patients with unilateral breast symptoms: an optimal imaging approach. Eur Radiol, 2020.PMID 32242274

The one-line answer

Definition — gland, not fat, with a ridge you can feel

Gynecomastia (GM) is a benign proliferation of the glandular tissue of the breast in men — gland is the diagnosis, fat alone is not.^[1]
Gynecomastia (GM) is characterized by enlargement of the male breast, caused by glandular proliferation and fat deposition — most clinical cases mix both, but the gland defines the disease.^[2]
Clinically, gynecomastia is characterized by the presence of a firm or rubbery, discrete, subareolar ridge of glandular tissue that is symmetrical in shape, freely movable, and nonadherent to skin or underlying tissue — feel for the ridge before naming it.^[3]
GM is characterized by enlargement of the male breast due to the proliferation of glandular ducts and stromal components — ducts plus stroma is the tissue the pathologist sees.^[4]
The main purpose of evaluating a patient with GM is to establish the diagnosis and differentiate true GM from pseudogynecomastia, exclude breast cancer, and detect the possible cause — true versus pseudo versus cancer is the first triage.^[10]
Breast examination should confirm the presence of palpable glandular tissue to discriminate GM from lipomastia (pseudo-gynecomastia) and rule out the suspicion of malignant breast tumor — the examination, not the scan, makes the first cut.^[1]

Mechanism — oestrogen stimulation against androgen brake

A hormonal imbalance between estrogens and androgens is the key hallmark of GM generation — remember imbalance, not absolute excess alone.^[2]
Gynecomastia is caused by an imbalance between the stimulatory effect of estrogen and the inhibitory effect of androgen at the breast tissue level — stimulation unopposed is the unit mechanism.^[3]
The main cause of GM during adolescence is physiological or pubertal GM, which is primarily attributed to an imbalance between estrogen and androgen activity — puberty is the same mechanism at the wrong hour.^[4]
The etiology of GM is attributable to physiological factors, endocrine tumors or dysfunctions, non-endocrine diseases, drug use or idiopathic causes — physiology, hormones, systemic disease, drugs, or none found.^[2]
An underlying pathology may be revealed in 45%-50% of adult men with GM, such as aggravating medications, systemic diseases, obesity, endocrinopathies, or malignancy — adult disease earns the cause hunt.^[10]

Epidemiology — three peaks, common in normal men, rising fast

It is a common condition, which may occur physiologically and shows three age peaks during a male's lifespan: infancy, puberty, and senescence — expect it at both ends and in the middle.^[10]
Gynecomastia may occur physiologically in the neonatal period, during puberty, and in old age — the same three peaks in the paediatric lens.^[3]
It is a frequent condition with a reported prevalence of 32-65%, depending on the age and the criteria used for definition — definition changes the count.^[1]
The prevalence of palpable gynecomastia was determined in 306 normal adult men ranging in age from 17-58 yr — this is the normal-men denominator.^[5]
Palpable breast tissue was present in 36% and was bilateral in all but 7 subjects — common and usually bilateral in normal men.^[5]
In the great majority of cases, the gynecomastia was 4 cm or less in diameter — small is the norm.^[5]
A diameter greater than 5 cm was distinctly unusual — size above 5 cm breaks the normal pattern.^[5]
With advancing age there was a progressive increase in the prevalence of gynecomastia — age is the gradient.^[5]
In those over the age of 44, the prevalence was 57% — more than half of older normal men have palpable tissue.^[5]
Overall, a total 17 601 males (age 0-80 years) were registered with an incident diagnosis of gynecomastia within the 20-year study period, corresponding to 880 new cases per year and an average 20-year incidence of 3.4 per 10 000 men (age 0-80 years) — the national-registry denominator.^[6]
The average annual incidence was 6.5/10 000 in postpubertal males age 16 to 20 years and 4.6/10 000 in males age 61 to 80 years, with a respective 5- and 11-fold overall increase in these 2 age groups over the 20-year period — the rise concentrates at puberty and senescence.^[6]
Gynaecomastia affects half of the male population at some stage in their life — half is the lifetime frame for counselling.^[9]
Gynaecomastia is the most common benign condition of the male breast and accounts for up to 80% of male breast referrals — the breast clinic denominator.^[13]
Gynaecomastia was more prevalent in the under twenties age group — referrals skew young.^[13]

Adolescent disease — transient, stressful, reassurance first

GM of infancy and puberty are common, benign conditions resolving spontaneously in the majority of cases — infancy and puberty usually need nothing.^[1]
GM of puberty is a common condition, affecting approximately 50% of mid-pubertal boys; in more than 90% of cases, it resolves spontaneously within 24 months — quote the half and the 90% at 2 years.^[1]
Gynecomastia (GM) is a common and continuously evolving condition that commonly occurs during adolescence — evolving is the warning against one-visit certainty.^[4]
It is the source of significant embarrassment and psychological stress in adolescent males — name the distress before the boy does.^[4]
Physiological GM is typically transient and resolves within several months, although it may take several years to resolve — months usually, years sometimes.^[4]
Since most cases of physiological gynecomastia regress spontaneously with time, reassurance is all that is necessary — reassurance is the treatment.^[3]
GM may also be caused by other pathological conditions and could be indicative of an endocrine disease — persistence or atypia breaks the reassurance rule.^[4]
The challenge for the physician is to distinguish physiological gynecomastia from those with an underlying pathology — that distinction is the whole adolescent job.^[3]
Most men are looking for reassurance that their condition is benign and that no intervention is required — offer psychological support as part of treatment, not as an afterthought.^[13]

Adult workup — the 43% with treatable cause set the standard

Gynaecomastia is a benign proliferation of glandular tissue of the breast; however, it is an important clinical observation because it can be the first symptom of an underlying disease — the first symptom framing sets the workup threshold.^[7]
Thirty-two men who did not have gynaecomastia when examined were excluded; leaving 786 men for final analyses — the examined denominator behind the workup numbers.^[7]
They underwent an andrological examination, ultrasound of the testicles and analysis of endogenous serum hormones levels — examination plus testicular ultrasound plus hormones is the modelled workup.^[7]
In 43% of men with adult onset of gynaecomastia (≥18 years) an underlying, and often treatable, cause could be detected — adult onset earns the full hunt.^[7]
In men younger at onset an underlying cause for gynaecomastia could be detected in merely 7.7% — young onset rarely hides disease, adult onset commonly does.^[7]
GM of adulthood is more prevalent among the elderly and proper investigation may reveal an underlying pathology in 45-50% of cases — the guideline range matches the cohort.^[1]
The purpose of GM assessment should be the detection of underlying pathological conditions, reversible causes (administration/abuse of aggravating substances), and the discrimination from other breast lumps, particularly breast cancer — pathology, reversible cause, cancer discrimination.^[1]
The medical history should include information on the onset and duration of GM, sexual development and function, and administration or abuse of substances associated with GM — onset, puberty, sex, substances.^[1]
The physical examination should detect signs of under-virilization or systemic disease — look beyond the breast.^[1]
We recommend that the physical examination should include the examination of the genitalia to rule out the presence of a palpable testicular tumor and to detect testicular atrophy — genitalia are mandatory, not optional.^[1]
Assessment should comprise a thorough medical history and physical examination of the breast and genitalia (including testicular ultrasound) — palpation misses tumours that ultrasound finds.^[1]
A set of laboratory investigations may integrate the evaluation: testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicular stimulating hormone (FSH), thyroid stimulating hormone (TSH), prolactin, human chorionic gonadotropin (hCG), alpha-fetal protein (AFP), liver and renal function tests — the full panel when the workup is warranted.^[1]
For pathological gynecomastia, treatment should be directed at the underlying cause, if possible — cause first, breast second.^[3]
Clinical evaluation must address diagnostic confirmation, search for an etiological factor and classify GM into severity grades to guide the treatment — confirm, find, grade, then treat.^[2]

Drugs are estimated to cause about 10 - 25% of all cases of gynecomastia — ask the drug history in every adult.^[8]
Most of the reported drug-gynecomastia associations were based on poor quality evidence — believe the short definite list, hold the long list lightly.^[8]
The drugs definitely associated with the onset of gynecomastia are spironolactone, cimetidine, ketoconazole, hGH, estrogens, hCG, anti-androgens, GnRH analogs and 5-α reductase inhibitors — memorise this fence before stopping a drug.^[8]
Medications probably associated with gynecomastia include risperidone, verapamil, nifedipine, omeprazole, alkylating agents, HIV medications (efavirenz), anabolic steroids, alcohol and opioids — probable means review, not reflex cessation.^[8]
Watchful waiting is recommended after treatment of underlying pathology or discontinuation of substances associated with GM — stop the cause, then wait before operating.^[1]

Imaging — selective, patterned, and routinely overused

Most male breast lesions can be diagnosed on clinical grounds; however, in certain cases, when physical examination is inconclusive, imaging may be helpful — clinical first, imaging for the equivocal.^[10]
Breast imaging may be used whenever the clinical examination is equivocal — the guideline gives the same boundary.^[1]
In suspicious lesions, core needle biopsy should be sought directly instead — suspicious skips imaging as the decider and goes to needle.^[1]
GM is seen in mammography as a subareolar opacity and three mammographic patterns of GM are described: nodular, dendritic, and diffuse, corresponding to florid GM of early onset, fibrous persistent GM, and GM due to exogenous estrogen administration, respectively — nodular is florid early, dendritic is fibrous persistent, diffuse is exogenous oestrogen.^[10]
In ultrasound (US), florid GM is depicted as a disk-shaped, hypoechoic area underlying the areola, whereas echogenicity of the lesions increases as fibrosis develops — hypoechoic disk early, echogenic late.^[10]
Both mammography and US are sensitive and specific to diagnose GM and distinguish it from breast cancer — either modality separates gland from cancer when needed.^[10]
When clinical findings are suggestive of malignancy or imaging findings are inconclusive, a histological confirmation should be sought — inconclusive imaging ends in tissue.^[10]
A retrospective study assessing the imaging of the male breast in 557 patients over a 10-year period found the overuse pattern behind the discourage-routine rule.^[11]
The modalities used were mammography in 65%, ultrasound in 51% and both in 26% — this is how often surgeons currently image.^[11]
Most examinations, 519, were BI-RADS 1 or 2, and 38 were BI-RADS 3 or higher — almost all imaging was benign.^[11]
Malignancies were diagnosed in five patients (0.89%) — under 1% cancer in an imaged male-breast cohort.^[11]
Imaging had a sensitivity of 80% and a specificity of 99% — specific, not sensitive, in this mixed cohort.^[11]
The positive predictive value was 44% and the negative predictive value 99.8% — a negative scan reassures, a positive scan still needs tissue.^[11]
Imaging is not warranted unless there are suspicious abnormalities — the overuse conclusion in one line.^[11]
Routine imaging of gynecomastia should be discouraged — do not scan the obvious bilateral pubertal breast.^[11]
A total of 628 patients with 518 mammograms and 423 ultrasounds were reviewed in the mammography-versus-ultrasound cohort.^[12]
The final diagnoses were: 19 carcinomas, 526 gynaecomastias, 84 other benign conditions and 25 normal — gynaecomastia dominates, cancer is uncommon.^[12]
Mammography was the most sensitive (94.7%) and ultrasound the most specific (95.3%) for detection of malignancy — mammo finds, ultrasound excludes.^[12]
Mammography and ultrasound, with a negative predictive value close to 100%, make it possible to avoid very many unnecessary surgical procedures in men — a negative workup avoids the operation.^[12]

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Core biopsy (CB) became the histological investigation of choice for men with unilateral disease — unilateral gets tissue when indicated.^[13]
Two hundred seventy-one consecutive male patients (mean age, 57 years) with unilateral breast symptoms underwent bilateral mammography — the unilateral-symptom experiment.^[18]
Of 271 male patients, 29 were pathologically diagnosed with breast cancer. There was no bilateral breast cancer — cancer is ipsilateral only in this series.^[18]
The sensitivity, specificity, positive and negative predictive values, and accuracy were 96.6%, 96.7%, 77.8%, 99.6%, and 96.7%, respectively, for unilateral review — unilateral-plate numbers.^[18]
The diagnostic performance of unilateral mammography is comparable with bilateral mammography in male patients with unilateral breast symptoms — the second plate adds no accuracy.^[18]
Unilateral mammography also has the advantage of reducing radiation exposure — one plate when one breast complains.^[18]

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Weight loss, reassurance, pharmacotherapy with tamoxifen and surgical correction are the therapeutic options — the full ladder in one line.^[2]
Watchful waiting is recommended after treatment of underlying pathology or discontinuation of substances associated with GM — waiting is active management after the cause is fixed.^[1]
T treatment should be offered to men with proven T deficiency — replace testosterone only when deficiency is proven.^[1]
The use of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs) and non-aromatizable androgens is not justified in general — the guideline does not endorse routine hormonal manipulation.^[1]
If gynecomastia persists in spite of the above measures and treatment becomes necessary, tamoxifen is the treatment of choice — persistent disease that needs drugs gets tamoxifen first.^[3]
Men with painful gynaecomastia were given 10 mg of tamoxifen for 3 months — the studied painful-disease regimen.^[9]
Thirteen men (median age 36) were placed on tamoxifen — small, young, painful cohort.^[9]
Ten patients responded well to tamoxifen — most painful cases improved.^[9]
One patient developed calf tenderness and stopped the medication — tolerability is good with rare stoppage.^[9]
Tamoxifen appears safe and effective in men with painful idiopathic or physiological gynaecomastia and should be considered as an initial option before contemplating surgery — painful recent disease gets tamoxifen before knife.^[9]
Surgical treatment is the therapy of choice for patients with long-lasting GM — persistence is the surgical indication.^[1]
We suggest surgical treatment only for patients with long-lasting GM, which does not regress spontaneously or following medical therapy — long-lasting and non-regressing is the fence.^[1]
For long-standing GM, the best results are generally achieved through surgery, combining liposuction and mammary adenectomy — fat plus gland needs both tools.^[2]
Reduction mammoplasty may be considered for resistant cases — resistant disease ends in reduction.^[3]
There were 70 mastectomies performed on 52 subjects in the double-donut series — bilateral disease dominates the operative cohort.^[14]
The average age was 47 (23-73) years old — adult operative population.^[14]
The average total volume of breast tissue excised via the previous technique was 97.4 cm3, this increased to 186.5 cm3 with the new technique — the extended incision resects nearly twice the tissue.^[14]
No necrosis of the NAC was seen and no wound infections resulted in complication — nipple and wound safety in this series.^[14]
Cosmetic satisfaction was seen in 98% of patients — satisfaction is high with the mastopexy-skin-reduction approach.^[14]

Cancer boundary — gynaecomastia is not premalignant

Male breast cancer is rare; GM should not be considered a premalignant condition — say this to every worried patient.^[1]
Review of 932 males with breast pathology was performed to identify cases of ADH — the male-ADH denominator.^[15]
Nineteen males were diagnosed with ADH from June 2003 to September 2018 — ADH in men is uncommon.^[15]
Median patient age at ADH diagnosis was 25 years (range 18-72 years) — young men with gynaecomastia carry the ADH in this series.^[15]
At a mean follow-up of 75 months (range 4-185 months), no patient developed breast cancer — excised gynaecomastia with ADH shows no cancers at 6 years.^[15]
Occurrence of male breast cancer, a rare disease, peaks at age 71 years — old-age cancer against young-adult gynaecomastia.^[16]
Familial cases usually have BRCA2 rather than BRCA1 mutations — BRCA2 is the male-breast gene.^[16]
Hyperoestrogenisation resulting from Klinefelter's, gonadal dysfunction, obesity, or excess alcohol, all increase risk as does exposure to radiation, whereas gynaecomastia does not — shared oestrogenic risks raise cancer, gynaecomastia itself does not.^[16]
Presentation is usually a lump or nipple inversion, but is often late, with more than 40% of individuals having stage III or IV disease — late lumps, not gynaecomastia, are the cancer story.^[16]
Because 90% of tumours are oestrogen-receptor-positive, tamoxifen is standard adjuvant therapy — male cancer is tamoxifen-responsive, which is a different tamoxifen from the gynaecomastia course.^[16]
Male breast cancer (MBC) is rare, accounting for less than 1% of all breast cancer but the incidence has increased worldwide — rare but rising.^[17]
BRCA2 carriers have 80 times the risk of the general population — the number that changes counselling and referral.^[17]
Men generally present with breast cancer at an older age compared with women — older than the female counterpart.^[17]

Exam pearls and pitfalls — what fails the viva

Never offer routine imaging for clinically obvious bilateral gynaecomastia without suspicious features — 519 of 557 examinations were BI-RADS 1 or 2 and routine imaging is discouraged.^[11]
Never skip the genital examination and testicular ultrasound in adult-onset disease — detection of a testicular tumor by palpation has low sensitivity and the 43% cause rate punishes the skippers.^[1]^[7]
Never start SERMs, aromatase inhibitors or non-aromatizable androgens as routine gynaecomastia therapy — the guideline does not justify them in general, whatever the clinic habit.^[1]
Never operate the recent pubertal breast that would have regressed — more than 90% resolve within 24 months and reassurance is all that is necessary.^[1]^[3]
Never delay tissue when the picture is suspicious — core needle biopsy goes directly instead of another scan.^[1]
Say the mechanism in one breath at the station: stimulatory oestrogen unopposed by inhibitory androgen at the breast, with ducts and stroma proliferating — then name the bucket for this patient.^[2]^[3]^[4]

References18Show

[1]Kanakis GA, et al. EAA clinical practice guidelines-gynecomastia evaluation and management. Andrology, 2019.PMID 31099174
[2]Barros AC, et al. Gynecomastia: physiopathology, evaluation and treatment. Sao Paulo Med J, 2012.PMID 22790552
[3]Leung AKC, et al. Gynecomastia in Infants, Children, and Adolescents. Recent Pat Endocr Metab Immune Drug Discov, 2017.PMID 28260521
[4]Metwalley KA, et al. Gynecomastia in adolescent males: current understanding of its etiology, pathophysiology, diagnosis, and treatment. Ann Pediatr Endocrinol Metab, 2024.PMID 38712491
[5]Nuttall FQ, et al. Gynecomastia as a physical finding in normal men. J Clin Endocrinol Metab, 1979.PMID 429488
[6]Koch T, et al. Marked Increase in Incident Gynecomastia: A 20-Year National Registry Study, 1998 to 2017. J Clin Endocrinol Metab, 2020.PMID 32754750
[7]Mieritz MG, et al. Gynaecomastia in 786 adult men: clinical and biochemical findings. Eur J Endocrinol, 2017.PMID 28179453
[8]Deepinder F, et al. Drug-induced gynecomastia: an evidence-based review. Expert Opin Drug Saf, 2012.PMID 22862307
[9]Hanavadi S, et al. The role of tamoxifen in the management of gynaecomastia. Breast, 2006.PMID 15998589
[10]Billa E, et al. Imaging in gynecomastia. Andrology, 2021.PMID 34033252
[11]Lapid O, et al. Overuse of imaging the male breast-findings in 557 patients. Breast J, 2015.PMID 25772378
[12]Muñoz Carrasco R, et al. Mammography and ultrasound in the evaluation of male breast disease. Eur Radiol, 2010.PMID 20571799
[13]Al-Allak A, et al. Gynaecomastia: a decade of experience. Surgeon, 2011.PMID 21843819
[14]Wyrick DL, et al. Changing practices: The addition of a novel surgical approach to gynecomastia. Am J Surg, 2018.PMID 29395029
[15]Coopey SB, et al. Atypical ductal hyperplasia in men with gynecomastia: what is their breast cancer risk? Breast Cancer Res Treat, 2019.PMID 30666539
[16]Fentiman IS, et al. Male breast cancer. Lancet, 2006.PMID 16488803
[17]Fox S, et al. Male breast cancer: an update. Virchows Arch, 2022.PMID 34458944
[18]Yoon B, et al. Male patients with unilateral breast symptoms: an optimal imaging approach. Eur Radiol, 2020.PMID 32242274

Gynaecomastia for Surgeons — Imbalance Mechanism, Pubertal Reassurance, 43% Adult Workup, Drug Lists, Selective Imaging and Long-Standing Surgery

The one-line answer

Definition — gland, not fat, with a ridge you can feel

Mechanism — oestrogen stimulation against androgen brake

Epidemiology — three peaks, common in normal men, rising fast

Adolescent disease — transient, stressful, reassurance first

Adult workup — the 43% with treatable cause set the standard

Imaging — selective, patterned, and routinely overused

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Cancer boundary — gynaecomastia is not premalignant

Exam pearls and pitfalls — what fails the viva

Gynaecomastia for Surgeons — Imbalance Mechanism, Pubertal Reassurance, 43% Adult Workup, Drug Lists, Selective Imaging and Long-Standing Surgery

The one-line answer

Definition — gland, not fat, with a ridge you can feel

Mechanism — oestrogen stimulation against androgen brake

Epidemiology — three peaks, common in normal men, rising fast

Adolescent disease — transient, stressful, reassurance first

Adult workup — the 43% with treatable cause set the standard

Imaging — selective, patterned, and routinely overused

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Cancer boundary — gynaecomastia is not premalignant

Exam pearls and pitfalls — what fails the viva

The one-line answer

Definition — gland, not fat, with a ridge you can feel

Mechanism — oestrogen stimulation against androgen brake

Epidemiology — three peaks, common in normal men, rising fast

Adolescent disease — transient, stressful, reassurance first

Adult workup — the 43% with treatable cause set the standard

Drugs — definite and probable lists with the 10 to 25% share

Imaging — selective, patterned, and routinely overused

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Cancer boundary — gynaecomastia is not premalignant

Exam pearls and pitfalls — what fails the viva

The one-line answer

Definition — gland, not fat, with a ridge you can feel

Mechanism — oestrogen stimulation against androgen brake

Epidemiology — three peaks, common in normal men, rising fast

Adolescent disease — transient, stressful, reassurance first

Adult workup — the 43% with treatable cause set the standard

Drugs — definite and probable lists with the 10 to 25% share

Imaging — selective, patterned, and routinely overused

Unilateral disease — biopsy the suspicious, spare the contralateral plate

Management ladder — reassure, watch, tamoxifen for pain, operate the persistent

Cancer boundary — gynaecomastia is not premalignant

Exam pearls and pitfalls — what fails the viva