Gynecomastia

What gynecomastia is

Gynecomastia is the growth of real breast gland tissue in a man. The European Academy of Andrology defines it in one line — "Gynecomastia (GM) is a benign proliferation of the glandular tissue of the breast in men" — and the emphasis belongs on "glandular", because the commonest thing mistaken for it is not glandular at all. Fat under the areola produces the same silhouette and needs nothing done about it.

The mechanism is a shift in the balance between oestrogen and androgen action at the breast, and it can arrive from either direction. Oestrogen activity can rise — most often through increased conversion of androgens to oestrogens by tissue aromatase, which is why it tracks with body fat, and occasionally through a tumour that secretes oestrogen or human chorionic gonadotropin. Androgen activity can fall, through primary testicular failure or a central cause. Or the binding can shift: the Mayo Clinic Proceedings review notes that sex hormone-binding globulin changes are the proposed mechanism in hyperthyroidism, chronic liver disease and with drugs such as spironolactone.

It is extremely common, and how common depends entirely on where you draw the line. The EAA guideline reports "a reported prevalence of 32-65%, depending on the age and the criteria used for definition". The Mayo review reports asymptomatic gynecomastia in "up to 70% in men aged 50 to 69 years", and describes a screening study in which "A screening for gynecomastia in 214 hospitalized adult men aged 27 to 92 years revealed that 65% had gynecomastia, defined in this study as nodule size greater than 2 cm; however, none of them were symptomatic." Symptomatic gynecomastia is much less common than that, and it is the symptomatic kind that brings men to a page like this.

The reassuring part, stated by the guideline rather than by us: "Male breast cancer is rare; GM should not be considered a premalignant condition." Gynecomastia does not turn into cancer. The reason breast cancer appears anywhere on this page is different and narrower — it is one of the things an enlarged male breast can turn out to be instead, and telling the two apart is part of what the first examination is for.

What you can tell, and what you cannot

There is one observation a man can usefully make and one he can usefully report. The observation is whether the enlargement is symmetrical or one-sided. The report is the timeline — when it started, how fast, whether it is tender, and what medication or substance changed in the months before. The EAA makes exactly that the content of the history: onset and duration, sexual development and function, and "administration or abuse of substances associated with GM".

Tenderness is worth knowing about because it misleads in a specific direction. Tender is the usual finding in active gynecomastia — the Mayo review describes the typical mound as "tender, firm, mobile" — and it settles over time as fibrous tissue replaces gland. So a lump that has stopped hurting has not necessarily improved; it may simply be older. Meanwhile people assume that pain means something sinister and its absence means safety, and neither follows.

Almost everything else requires a hand that is not yours. Whether what you are feeling is a discrete subareolar disc or diffuse fat. Whether it is mobile or fixed. Whether it sits centrally under the areola or off to one side. Whether the overlying skin has changed. Whether there is anything in the axilla. And whether the testes are normal in size, consistency and contour — which is the part of the examination men least expect and the guideline rates most highly.

The four structured findings below are the ones a clinician makes. They are short on purpose and they are all physical-examination findings rather than symptoms, because on this condition the symptoms do not separate the harmless case from the one worth investigating and the examination does.

The signs that are specific — and none of them are self-assessable

A discrete subareolar disc of glandular tissue

The finding that separates gynecomastia from everything that merely looks like it. The Mayo review describes what palpation usually demonstrates: a tender, firm, mobile, disclike mound located centrally under the nipple-areolar complex and not as hard as breast cancer. Pseudogynecomastia gives diffuse enlargement with no subareolar nodule at all.

A mass that is unilateral, hard, fixed or peripheral

The combination that changes the pathway. Where palpable masses are unilateral, hard, fixed, peripheral to the nipple and associated with nipple discharge, skin changes or lymphadenopathy, the review states that breast cancer should be suspected and thorough evaluation is recommended. Each of those words is an examination finding rather than something visible.

A palpable testicular tumour, or testicular atrophy

The examination men do not expect to be part of a breast complaint, and the one the guideline grades at its highest evidence quality. The EAA recommends that physical examination include the genitalia to rule out a palpable testicular tumour and to detect testicular atrophy — the second of which is also how a hypogonadal cause first shows itself.

A testicular lesion on ultrasound that palpation missed

The reason the guideline does not stop at the examining hand. It recommends that genital examination be aided by a testicular ultrasound specifically because the detection of a testicular tumour by palpation has low sensitivity. This is the finding a man has no route to on his own, and it is the one with the shortest useful window.

The diagnostic criteria, quoted

Each criterion below is the guideline’s own wording, not a summary of it. Our reading follows underneath, so you can weigh one against the other.

1. What gynecomastia is, and what the assessment is for

   “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.”

   Three purposes and they are in priority order. Find anything underneath it. Find anything reversible causing it. And establish that it is gynecomastia rather than another kind of lump. Notice what is not on the list: deciding on treatment. The guideline treats assessment as an end in itself, which is the opposite of how the subject is usually presented, where the enlargement is a cosmetic problem and the workup is optional.

2. The examination is of the breast and the genitalia, together

   “Assessment should comprise a thorough medical history and physical examination of the breast and genitalia (including testicular ultrasound).”

   One sentence, and the parenthesis is the part men are surprised by. A breast complaint leads to a genital examination and a scrotal scan because the breast finding can be downstream of something in the testis. If you are offered an assessment of gynecomastia that does not include this, the guideline text is worth having with you.

3. Confirm it is gland, and rule out the other thing

   “We recommend that 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”

   One of only two recommendations in the whole guideline graded at high-quality evidence, and it is an examination rather than a test. Two jobs in one sentence: establish there is real gland there, and exclude a malignant tumour. If the answer to the first is no — diffuse subareolar fat, no nodule — the Mayo review’s position is that these men "do not need additional work-up and only require reassurance", and the rest of this page stops applying to you.

4. Examine the testes

   “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”

   The other recommendation at ⊕⊕⊕⊕, and the reason this page exists in the shape it does. The EAU testicular cancer guideline approaches the same point from the cancer side: gynaecomastia "may be present in a small number of patients" and "Clinical assessment should thus include abdominal, chest and supraclavicular examination". Small numbers, high stakes, short examination.

5. And scan them, because the hand is not enough

   “We recommend that genitalia examination is aided by a testicular ultrasound, as the detection of a testicular tumor by palpation has low sensitivity”

   Strong recommendation on low-quality evidence, which is a guideline saying the balance of benefit and harm is clear even though the studies are thin — an ultrasound is painless, quick and cheap, and the thing it is looking for is treatable early. This is also the point at which the sources on this page part company: the Mayo review takes the opposite line and says to scan only if you can feel something. Both are printed below.

6. A plausible cause does not close the investigation

   “We recommend that the identification of an apparent reason for GM in adulthood, including the use of medication known to be associated with GM, should not preclude a detailed investigation”

   The recommendation this page is organised around. Roughly half of adult cases turn out to have an underlying pathology on proper investigation, and a man who has found his drug on a list has not investigated, he has stopped. The temptation is strongest exactly where the explanation is most available — on testosterone therapy, on finasteride, drinking heavily, carrying weight — and the label of the drug agreeing that it causes breast changes makes it feel settled. It is not settled.

7. What the laboratory set is, when one is done

   “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.”

   Note the two that a general hormone panel will not include and that are here for a specific reason: human chorionic gonadotropin and alpha-fetoprotein are tumour markers. They are on the list because of what the examination and the ultrasound are also looking for. Note also the grade — this is a weak recommendation on low-quality evidence, which is the guideline being honest that the panel is sensible rather than proven.

Where the guidelines disagree

On these points there is no consensus to report. Both positions are printed with the wording each body used.

What the examining hand is distinguishing between

Three things present as an enlarged male breast and they are told apart by palpation, not by looking. This table is here so you know what the examination is for — not so you can perform it on yourself, which is the one thing the descriptions below cannot be used for.

Read the first and third rows together and then read this: in the case series the review cites, "All breast cancer cases in that series presented with a dominant mass on clinical examination or other signs suggestive of malignancy." That is reassuring about what examination can catch and it is not permission to substitute your own. The whole distinction in row one versus row two turns on whether there is a discrete disc under the areola or diffuse softness, and that is a judgement made by someone who has felt a hundred of both. Sources: [2] [1]

The fifteen recommendations, with the strength and evidence grade attached

The European Academy of Andrology’s 2019 clinical practice guideline, condensed to the operative clause of each recommendation with its own grading intact. The symbols are the guideline’s: ⊕○○○ very low quality evidence, ⊕⊕○○ low, ⊕⊕⊕○ moderate, ⊕⊕⊕⊕ high.

Three things stand out when the grades are left on. The two recommendations graded at the guideline’s highest evidence quality are both examinations — of the breast and of the genitalia. The ultrasound recommendation is Strong but rests on low-quality evidence, which is the guideline telling you it thinks the balance of benefit and harm is clear even though the studies are not. And the recommendation against SERMs, aromatase inhibitors and non-aromatizable androgens is also Strong — a guideline saying do not, rather than declining to say do. Sources: [1]

What was actually found when adults with gynecomastia were investigated

Two published figures about how often investigation turns something up, and one breakdown of what. Read the footnote before quoting any of them: the guideline and the review disagree, and the review says its own breakdown is imprecise.

The review attaches its own warning to the middle rows and it should travel with them: "The frequency distribution of these etiologies is imprecise because of the small number of cases reported in the literature and may vary widely across publications and practice settings." Note also that the 58% idiopathic figure and the 45–50% pathology figure are not in conflict — one is a series of men aged 19 to 29, the other is adulthood generally, and the guideline says prevalence of an underlying cause rises with age. The 1% malignancy rate is among men who were referred for imaging, not among all men with gynecomastia. Sources: [2] [1]

Substances and drugs named in the sources we read

Not an exhaustive list of everything associated with gynecomastia — it is what the documents opened for this page actually name. Two of them are drugs a man reading a men’s health site is disproportionately likely to be taking.

This table is deliberately not a complete drug list, and completeness would be the wrong goal anyway. The guideline’s first recommendation is that identifying an apparent reason — "including the use of medication known to be associated with GM" — should not preclude a detailed investigation. Finding your drug on a list is a reason to go and be examined, not a reason to stop. The two label rows matter most to this site’s readers: testosterone therapy and finasteride are both on it, both by their own manufacturers’ admission, and neither entry means a breast change on treatment can be assumed to be the drug. Sources: [2] [5] [6]

The tests, and what each one answers

What else an enlarged male breast turns out to be

This list splits into two halves and both matter. The first half is things that are not gynecomastia at all and are separated by palpation — fat, a discrete benign lump, a malignancy. The second half is conditions that genuinely cause gynecomastia and are the reason the guideline says a plausible explanation does not close the case. A five-year review of every male mammogram at one centre found a 1% rate of malignancy, with gynecomastia accounting for 62% of the benign findings and the rest spread across lipomas, cysts, inflammation, ductal ectasia, haematomas and fat necrosis.

Pseudogynecomastia (lipomastia)

The commonest thing mistaken for it, and the one where the answer is genuinely nothing. The Mayo review defines it as "accumulation of subareolar fat without real proliferation of glandular tissue" and describes the finding: "Examination of these patients reveals diffuse breast enlargement without a subareolar palpable nodule. These patients do not need additional work-up and only require reassurance." A hand tells these apart in seconds; a mirror never does.

Male breast cancer

Rare, and the reason a set of specific features is worth knowing. The review’s trigger is a combination rather than any one thing: masses that are "unilateral, hard, fixed, peripheral to the nipple, and associated with nipple discharge, skin changes, or lymphadenopathy". The guideline is clear that gynecomastia itself does not lead here — "Male breast cancer is rare; GM should not be considered a premalignant condition" — so this is a parallel possibility, not a progression.

A testicular tumour

The one that changes the urgency, and the reason the guideline puts a genital examination and a scrotal ultrasound into the workup for a breast complaint. The EAU testicular cancer guideline records that gynaecomastia "may be present in a small number of patients" and that "Clinical assessment should thus include abdominal, chest and supraclavicular examination". Small numbers and a short examination, against a diagnosis where time matters.

Hypogonadism

The commonest identified cause in the young-adult series the Mayo review reports, at 25% of cases. It arrives from the androgen side rather than the oestrogen side, and it is the reason testicular atrophy is one of the two things the guideline asks the genital examination to look for. It is also a separate diagnosis with its own criteria, which our hypogonadism page sets out — two morning samples, symptoms and signs, and LH to separate a testicular cause from a central one.

Hyperprolactinaemia

Nine per cent of the same series, and the reason prolactin is on the guideline’s laboratory list. A raised prolactin points at the pituitary and can indicate a prolactin-secreting lesion, which is treatable and which will not be found by anyone who accepted a drug explanation and stopped. It also suppresses testosterone, so it can produce the picture from two directions at once.

Chronic liver disease, and thyroid disease

Both alter sex hormone-binding globulin and with it the free testosterone to oestrogen balance — the Mayo review names hyperthyroidism and chronic liver disease together with spironolactone as sharing that mechanism. Liver and renal function tests and a thyroid-stimulating hormone are on the guideline’s laboratory list for this reason, and both conditions matter considerably more than the breast finding that led to them.

Testosterone therapy itself

Named on the label rather than inferred: DEPO-Testosterone’s Precautions state that "Gynecomastia may develop and occasionally persists in patients being treated for hypogonadism", and gynecomastia appears again in its Adverse Reactions. The word "persists" is the one to notice — this is not always a finding that reverses when the dose changes. It is also the archetypal case where an obvious explanation is available and the guideline says it does not end the investigation.

Finasteride and other drugs

The PROPECIA label instructs physicians to tell patients to "promptly report any changes in their breasts such as lumps, pain or nipple discharge" and records that "Breast changes including breast enlargement, tenderness and neoplasm have been reported". Note the label’s own instruction is to report and be assessed, not to assume the drug. The Mayo review adds spironolactone, bicalutamide, alcohol, marijuana, heroin, methadone, amphetamines and phytoestrogen-containing herbal supplements.

What treatment means here

Numbers this page will not give you

Each of these is a figure other pages state confidently. Each is omitted here because no source we could open supports one.

How much breast tissue counts as gynecomastia?

No diameter is printed, because the published figures are definitions rather than findings and they do not agree. The Mayo review states the problem directly: "Variation in reported prevalence across studies is attributed to variations in the size of the palpable breast tissue used to define gynecomastia and to population characteristics such as age and setting of treatment". It gives one worked example — a screening study of 214 hospitalised men that defined gynecomastia as a nodule greater than 2 cm and found 65% of them had it, none symptomatic. A threshold printed here would be one study’s convention presented as a fact about your body.

What is the chance that mine is cancer?

No individual probability is given because none is derivable from what we could open. The guideline states that male breast cancer is rare and that gynecomastia is not a premalignant condition. The only rate in our sources is from a five-year review of all male mammographic findings at one centre, where 1% were malignant — and that denominator is men who were already referred for imaging, which is not you and not all men with an enlarged breast. What can be said usefully is what triggers concern rather than what the odds are, and that is in the first table.

How long before it goes away on its own?

No timeline is printed for an adult. The 24-month figure quoted everywhere belongs to adolescence — the guideline’s Statement S3 is about pubertal gynecomastia, where "in more than 90% of cases, it resolves spontaneously within 24 months". For adults the Mayo review says only that the condition is usually self-limited and that fibrous tissue eventually replaces gland, and it is explicit about the gap when it comes to follow-up: "Although evidence is lacking to support a recommendation for follow-up intervals, 6 months seems reasonable." That sentence contains its own caveat and we are not going to strip it.

What dose of tamoxifen or anastrozole should I take?

No dose appears anywhere on this page for any drug used off-label here, and the guideline recommends against the whole class: SERMs, aromatase inhibitors and non-aromatizable androgens are not recommended in general, as a strong recommendation. Our own compound pages record the relevant labelled evidence: ARIMIDEX’s only randomised controlled male trial, in 80 boys with pubertal gynecomastia, showed no statistically significant difference from placebo on its primary endpoint, and the label says efficacy "has not been demonstrated". There is no dose here to state because there is no established regimen to state one for.

Can I tell from feeling it myself whether it is gland or fat?

This page prints the descriptions a clinician uses and will not turn them into a self-examination. The distinction is between a discrete, mobile, disclike mound sitting centrally under the areola and diffuse enlargement with no subareolar nodule at all — a judgement made by someone with a trained hand and a comparison set, on a body that is not their own. The guideline builds its whole pathway on that finding being made properly, grading it at its highest evidence quality, and a wrong answer sends a man down the wrong path in either direction.

Frequently asked questions

Is gynecomastia dangerous?

In itself, no. The European Academy of Andrology states it plainly as one of its five summary statements: "Male breast cancer is rare; GM should not be considered a premalignant condition." Gynecomastia does not turn into anything. The reason it still warrants assessment is different — proper investigation of adult gynecomastia reveals an underlying pathology in "approximately 45-50% of the cases", and the list of possibilities includes a testicular tumour, hyperprolactinaemia, liver disease and hypogonadism. The enlargement is benign; what is occasionally behind it is not, and finding that is the entire purpose of the assessment.

Why would a doctor examine my testicles for a breast problem?

Because the breast finding can be downstream of something there, and because it is one of only two recommendations in the guideline graded at the highest evidence quality. The EAA recommends that examination "include the examination of the genitalia to rule out the presence of a palpable testicular tumor and to detect testicular atrophy". It then goes further and asks for a scan alongside, "as the detection of a testicular tumor by palpation has low sensitivity" — so the hand alone is not considered adequate for the job. The EAU testicular cancer guideline reaches the same place from the other side, noting that gynaecomastia "may be present in a small number of patients".

Is it gynecomastia or just fat?

That is the first question and it is settled by palpation. True gynecomastia usually presents as "a palpable, tender, firm, mobile, disclike mound of tissues" sitting centrally under the nipple-areolar complex. Pseudogynecomastia, or lipomastia, is "accumulation of subareolar fat without real proliferation of glandular tissue", and examination "reveals diffuse breast enlargement without a subareolar palpable nodule". The practical difference is large: the review states that men with pseudogynecomastia "do not need additional work-up and only require reassurance", while true gynecomastia in an adult carries roughly a one-in-two chance of an underlying cause worth finding.

My testosterone or finasteride is obviously the cause — do I still need to be checked?

The guideline’s answer is yes, and it made that its first recommendation for exactly this situation: identifying an apparent reason, "including the use of medication known to be associated with GM, should not preclude a detailed investigation", graded Strong on moderate-quality evidence. Both drugs do list it. The DEPO-Testosterone label states that "Gynecomastia may develop and occasionally persists in patients being treated for hypogonadism", and the PROPECIA label instructs physicians to tell patients to report breast lumps, pain or nipple discharge promptly. Note what the finasteride label asks for — reporting and assessment, not assuming the drug. A source we also cite takes the opposite view, holding that a clear temporal link to a known culprit can "obviate the need for extensive and costly evaluation"; this page prints both and leans conservative.

When should an enlarged male breast be checked urgently?

When the features point somewhere else. The combination the Mayo review names is masses that are "unilateral, hard, fixed, peripheral to the nipple, and associated with nipple discharge, skin changes, or lymphadenopathy" — in that situation "breast cancer should be suspected and thorough evaluation is recommended", and the guideline’s route from there is core needle biopsy rather than more imaging. The other urgent picture is any testicular abnormality alongside the breast change. Neither of those is a reason to panic about the common case; they are the specific patterns worth acting on quickly.

How common is gynecomastia in men?

Very, and the range tells you the definitions differ rather than the men. The guideline reports "a reported prevalence of 32-65%, depending on the age and the criteria used for definition". The Mayo review reports asymptomatic gynecomastia at "up to 70% in men aged 50 to 69 years", and describes a screening study of 214 hospitalised men aged 27 to 92 in which 65% had gynecomastia when it was defined as a nodule larger than 2 cm — and "none of them were symptomatic". Symptomatic gynecomastia, which is what brings men to be assessed, is much less common than any of those numbers. This page does not print a single figure because the figure depends on the diameter someone chose.

Will tamoxifen or an aromatase inhibitor get rid of it?

The guideline recommends against, as a strong recommendation: "We do not recommend the use of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), or non-aromatizable androgens in the treatment of GM in general". The best-quality male evidence on the aromatase inhibitor route is on the ARIMIDEX label itself — a randomised, double-blind, placebo-controlled study in 80 boys with pubertal gynecomastia, in which after 6 months there was no statistically significant difference in the proportion achieving a 50% or greater reduction, and the label concludes that efficacy "has not been demonstrated". There is one dissenting position among our sources: the EAU lists mesterolone and dihydrotestosterone gel as useful specifically in painful gynaecomastia. No dose for any of these appears on this page.

Will it go away if I lose weight or stop the drug?

Sometimes, and the guideline’s recommendation after treating a cause is to wait rather than to act: "watchful waiting after treatment of underlying pathology or discontinuation of the administration/abuse of substances associated with GM". The natural history in the Mayo review is that gynecomastia "is a benign condition and is usually self-limited" and that over time fibrotic tissue replaces the glandular proliferation and tenderness resolves. Two caveats. That last sentence describes tenderness settling, not the lump disappearing — once fibrous tissue has replaced gland, there is less for anything to reverse. And the review is explicit about how weak the follow-up evidence is: "Although evidence is lacking to support a recommendation for follow-up intervals, 6 months seems reasonable."

Sources

1. [1]Kanakis GA, Nordkap L, Bang AK, et al. EAA clinical practice guidelines — gynecomastia evaluation and management. Andrology. 2019;7(6):778–793. PMID 31099174 — five statements and fifteen GRADE-based recommendations, quoted here from the structured abstract including the strength and evidence-quality symbols.
2. [2]Johnson RE, Murad MH. Gynecomastia: pathophysiology, evaluation, and management. Mayo Clin Proc. 2009;84(11):1010–1015. PMID 19880691, free full text PMC2770912 — the source of the palpation descriptions, the breast cancer suspicion features, the aetiology breakdown in young adults and the contrary position on scrotal imaging.
3. [3]European Association of Urology, Guidelines on Testicular Cancer — chapter 5, Diagnostic evaluation. Section 5.1: "Gynaecomastia may be present in a small number of patients. Clinical assessment should thus include abdominal, chest and supraclavicular examination."
4. [4]European Association of Urology, Guidelines on Sexual and Reproductive Health — chapter 3, Male Hypogonadism, section 3.4.3.b on testosterone formulations, which lists mesterolone and dihydrotestosterone gel as useful in gynaecomastia because neither aromatises to oestrogen.
5. [5]PROPECIA (finasteride) tablets, 1 mg — FDA prescribing information, Organon LLC, NDA 020788, via DailyMed. Section 17: "Physicians should instruct their patients to promptly report any changes in their breasts such as lumps, pain or nipple discharge."
6. [6]DEPO-Testosterone (testosterone cypionate injection) — FDA label, Pharmacia & Upjohn, ANDA085635, via DailyMed. Precautions: "Gynecomastia may develop and occasionally persists in patients being treated for hypogonadism." Adverse Reactions lists gynecomastia under Endocrine and urogenital.