Andrew Siegel MD 3/30/19
In females, the breasts (mammary glands) contribute to the alluring female form and allow ready access for the hungry infant, oddly an erogenous zone as well as a feeding zone.
1. chest wall 2. pectoral muscles 3. glandular tissue (lobules) 4. nipple 5. areola 6. ducts 7. fatty tissue 8. skin
Image above: by Original author: Patrick J. Lynch. Reworked by Morgoth666 to add numbered legend arrows. – Patrick J. Lynch, medical illustrator, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=2676813
But men, too, have breasts, areolas and nipples, yet male breasts lack glandular tissue (lobules) and have ducts that are blind-ending and incapable of lactation and providing nutrition to the infant. This begs the question of why men even have breasts in the first place. Furthermore, as desirable to the female form as breasts are, enlarged male breasts are viewed by most as unsightly and unattractive.
So why do men have breasts?
Both genders start out initially as female. In the absence of the male hormone testosterone (T), the fetus remains female (the default human model), and only in the presence of T does the fetus develops into a male. However, breasts, areolas and nipples in their rudimentary form are present before T shapes cells into male organs. So, men have breasts, areolas and nipples because they were already present before maleness set in. Consider them nature’s evolutionary bonus!
What are sex hormones?
The main male sex hormone is T and the main female sex hormone estrogen (E). However, males have some E and females have some T. T takes on two pathways in the body: Much of T is converted to dihydrotestosterone (DHT), the more potent and activated form. Some T is converted to E by virtue of the enzyme aromatase.
What are man boobs?
Man boobs—a.k.a. gynecomastia in medical speak—are a benign proliferation of glandular breast tissue. Gynecomastia is the most common breast condition in men. True gynecomastia—several centimeters or more of dense, firm, rubbery glandular tissue surrounding the areola—is distinguished from pseudo-gynecomastia, in which breast enlargement occurs due to fat deposition, without the presence of glandular tissue. Gynecomastia most commonly involves both breasts, although on occasion it can occur on just one side.
Under what circumstances do man breasts, which are supposed to be rudimentary and undeveloped, grow substantially?
Gynecomastia is seen in three distinct populations: newborns, adolescents and adults. Breast tissue proliferation is present in the vast majority of newborns because of residual maternal female hormone E in the body, which is depleted in a matter of a few weeks, making the situation self-limited. Gynecomastia is also seen during puberty in about 50% of adolescent boys, due to a delayed T surge relative to E activity, with spontaneous resolution in most. However, at this sensitive age, the presence of man boobs on prominent display in the middle-school locker room negatively impacts self-image and self-esteem and can be devastating psychologically and emotionally. The third population that develops man boobs is aging men, present to some extent in more than 50% after age 50, typically due to weight gain, decreased T levels, increased E levels, and altered T/E ratios.
Adolescent gynecomastia
Image above: David Andrew Copeland, Dr. Mordcai Blau http://www.gynecomastia-md.com [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)]
It is vital to make sure that male breast enlargement is not due to male breast cancer, which can occur on rare occasions. Cancer most often causes a hard mass within the breast tissue of one breast, sometimes with skin dimpling, and at times, lymph node enlargement –as opposed to gynecomastia that causes none of the aforementioned signs.
How is the extent of gynecomastia graded?
Grade I: minimal breast growth without drooping (ptosis in medical speak)
Grade II: moderate growth without drooping
Grade III: severe enlargement with drooping
Grade IV: severe enlargement with significant drooping
What is the main factor that underlies male breast growth?
In both sexes, the main driving factor for breast development is hormonal—E activity and the ratio between E and T. This explains normal female breast development at puberty (surge of E) as well as newborn, adolescent, and senior gynecomastia, which are associated with increased levels of E and altered ratio of E/T.
What medical issues give rise to gynecomastia?
There are 4 scenarios that can cause gynecomastia: conditions that cause excess E; conditions that cause low T; chronic medical conditions; and certain medications.
Thyroid disorders, e.g., hyperthyroidism, often increase sex hormone binding globulin (SHBG)—the protein that binds T and E—altering E/T ratio (since T is bound tighter than E), often giving rise to breast enlargement. Certain tumors of the testes (Leydig, Sertoli cell and occasionally germ cell tumors that secrete human chorionic gonadotropin [HCG]) as well as some adrenal tumors can cause gynecomastia. Carrying excessive weight and fat – particularly visceral abdominal fat (“beer belly”) – is a major risk factor for gynecomastia, as visceral fat contains an abundance of hormones including aromatase, the enzyme that converts T to E. Men with large bellies consequently are often found to have low T and high E that can result in “emasculation,” with loss of sex drive, diminished erections, loss of penile length and the presence of man boobs.
Gynecomastia due to central obesity
Attribution: commons.wikimedia.org/wiki/File:Central_Obesity_008.jpg
Dysfunction of the testes, hypothalamus and pituitary can give rise to low T and promote gynecomastia.
Chronic medical conditions—including kidney disease and cirrhosis—often cause gynecomastia along with many other symptoms.
Numerous medications may give rise to male breast enlargement: HCG, estrogens, human growth hormone, anabolic steroids, finasteride and dutasteride, androgen deprivation therapy medications, spironolactone, cimetidine, proton pump inhibitors, digoxin, verapamil, alcohol, and opioids.
How is gynecomastia evaluated?
Visual inspection is used to determine the extent of enlargement and drooping and physical examination to ensure the absence of an underlying breast mass. It is important to do laboratory testing, including liver, kidney and thyroid function tests as well as total T, free T, SHBG, E, luteinizing hormone (LH), prolactin, HCG.
How is gynecomastia treated?
If a specific underlying medical condition or hormonal abnormality is identified, it needs to be addressed. If the gynecomastia is drug induced, the culprit medication needs to be stopped. If due to obesity, commonsense solutions are weight loss and exercise.
The goal of medical therapy is to modulate the E/T ratio and this can be done with the use of medications including clomiphene (selective estrogen receptor modulator—SERM); tamoxifen (SERM plus blocks action of E on breast tissue); danazol (androgen receptor agonist); anastrozole (aromatase enzyme inhibitor), depending on the specific circumstance.
At times, surgery may be the only solution for gynecomastia. In general, liposuction of excessive fatty and glandular tissue is used successfully for mild-moderate gynecomastia whereas liposuction with excision of excessive skin or surgical excision (reduction mammoplasty) is used for severe gynecomastia with drooping.
Before and after surgical treatment
Attribution of image above: JMZ1122 Dr. Mordcai Blau http://www.gynecomastia-md.com [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
Wishing you the best of health,
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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery. He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.
Dr. Siegel’s newest book: PROSTATE CANCER 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families
Preview of Prostate Cancer 20/20
Video trailer for Prostate Cancer 20/20
Dr. Siegel is the author of 4 other books:
PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food
MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health
THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health
Andrew Siegel MD Amazon author page
Prostate Cancer 20/20 on Apple iBooks
Our Greatest Wealth Is Health 
