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Gynecomastia

Gynecomastia is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Gynecomastia rather than just read about it. In short: Gynecomastia (also spelled gynaecomastia) is the non-cancerous enlargement of one or both breasts in men due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Physically speaking, gynecomastia is completely benign, but it is associated with significant psychological distress, social stigma, and dysphoria.

Gynecomastia — main illustration
Gynecomastia — illustration

Key takeaways

  • Gynecomastia belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Gynecomastia to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Gynecomastia from memory before moving on to harder problems.

Reference excerpt

Gynecomastia (also spelled gynaecomastia) is the non-cancerous enlargement of one or both breasts in men due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Physically speaking, gynecomastia is completely benign, but it is associated with significant psychological distress, social stigma, and dysphoria. Gynecomastia can be normal in newborn male babies due to exposure to estrogen from the mother, in adolescent boys going through puberty, in older men over the age of 50, and in obese men. Most occurrences of gynecomastia do not require diagnostic tests. Abnormal hormone changes that cause gynecomastia may be caused by any condition that leads to an increase in the ratio of estrogens/androgens such as liver disease, kidney failure, thyroid disease and some non-breast tumors. Alcohol and some drugs can also cause breast enlargement. Other causes may include Klinefelter syndrome, metabolic dysfunction, or a natural decline in testosterone production. This may occur even if the levels of estrogens and androgens are both appropriate, but the ratio is altered. Gynecomastia is the most common benign disorder of the male breast tissue and affects 35% of men, being most prevalent between the ages of 50 and 69. It is normal for up to 70% of adolescent boys to develop gynecomastia to some degree. Of these, 75% resolve within two years of onset without treatment. If the condition does not resolve within 2 years, or if it causes embarrassment, pain or tenderness, treatment is warranted. Medical treatment of gynecomastia that has persisted beyond two years is often ineffective. Gynecomastia is different from "pseudogynecomastia", which is commonly present in men with obesity. Medications such as aromatase inhibitors are effective, even in rare cases of gynecomastia from disorders such as aromatase excess syndrome or Peutz–Jeghers syndrome, but surgical removal of the excess tissue can be needed to correct the condition. In 2019, 24,123 male patients underwent the procedure in the United States, accounting for a 19% increase since 2000.

Definition Gynecomastia is the abnormal non-cancerous enlargement of one or both breasts in men due to the growth of breast tissue as a result of a hormone imbalance between estrogen and androgen. Gynecomastia is different from "pseudogynecomastia", which is defined as an excess of skin and/or adipose tissue in the male breasts without the growth of true glandular breast tissue; this is commonly associated with obesity and can be ruled out by physical exam.

Signs and symptoms In gynecomastia, there is always enlargement of one or both breasts, symmetrically or asymmetrically, in a man. A soft, compressible, and mobile mass of breast tissue is felt under the nipple and its surrounding skin in contrast to softer fatty tissue, which is not associated with a mass. It may also be accompanied by breast tenderness or nipple sensitivity, which is commonly associated with gynecomastia observed in adolescents, typically early in development. Gynecomastia that is painful, bothersome, rapidly-growing, associated with masses in other areas of the body, or persistent should be evaluated by a clinician for potential causes. Dimpling of the skin, nipple discharge, and nipple retraction are not typical features of gynecomastia and may be associated with other disorders. Milky discharge from the nipple is not a typical finding, but may be seen in a gynecomastic individual with a prolactin secreting tumor. An increase in the diameter of the areola and asymmetry of the chest are other possible signs of gynecomastia. Much of the research on gynecomastia has focused on its causes and treatment, but little has explored its effects on mental health and overall quality of life. Gynecomastia has psychosocial implications that may be particularly challenging for adolescents who are experiencing physical maturation and self-identity formation, which includes body image disturbances, negative attitudes towards eating, self-esteem problems, social withdrawal, anxiety, and shame. Men with gynecomastia may appear anxious or stressed due to concerns about its appearance and the possibility of having breast cancer. Particular studies suggest that gynecomastia can lead to various psychological and social challenges, such as depression, anxiety and disordered eating.

Causes Gynecomastia is thought to be caused by an altered ratio of estrogens to androgens mediated by an increase in estrogen action, a decrease in androgen action, or a combination of these two factors. Estrogen and androgens have opposing actions on breast tissue: estrogens stimulate proliferation while androgens inhibit proliferation. The cause of gynecomastia is unknown in around 25% of cases. Known causes can be physiologic (occurring normally) or non-physiologic due to underlying pathologies such as drug use, chronic disease, tumors, or malnutrition.

Physiologic Physiologic or normal gynecomastia can occur at three timepoints in life: shortly after birth in both female and male infants, during puberty in adolescent males, and in older adults over the age of 60.

Newborns 60–90% of male and female newborns may show breast development at birth or in the first weeks of life. During pregnancy, the placenta converts the androgenic hormones dehydroepiandrosterone (DHEA) and DHEA sulfate to the estrogenic hormones estrone and estradiol, respectively; after the placenta produces these estrogens, they are transferred into the baby's circulation, thereby leading to temporary gynecomastia in the baby. In some infants, neonatal milk (also known as "witch's milk") can leak from the nipples. The temporary gynecomastia seen in newborn babies usually resolves after two or three weeks.

Adolescents

Hormonal imbalance (elevated ratio of estrogen to androgen) during early puberty, either due to decreased androgen production from the adrenals and/or increased conversion of androgens to estrogens, leads to transient gynecomastia in adolescent males. It can occur in up to 65% of adolescents as early as age 10 and peaks at ages 13 and 14. It is self-limited in 75–90% of adolescents. Usually, it resolves spontaneously within 1 to 3 years as pubertal progression increases testosterone levels and causes regression of breast tissue. By age 17, only 10% of adolescent males have persistent gynecomastia.

… excerpt ends here. Continue reading the full article.

Illustrations

Gynecomastia illustration
Gynecomastia: Gynecomastia of boys going through puberty
Gynecomastia of boys going through puberty
Gynecomastia: An exceptional case of extreme gynecomastia in a 63-year-old man, treated with the nonsteroidal antiandrogen flutamide for prostate cancer. (a) With flutamide, (b) after discontinuation of flutamide.[34] More than 90% of cases of gynecomastia with nonsteroidal antiandrogens including flutamide are mild to moderate.[35][36]
An exceptional case of extreme gynecomastia in a 63-year-old man, treated with the nonsteroidal antiandrogen flutamide for prostate cancer. (a) With flutamide, (b) after discontinuation of flutamide.[34] More than 90% of cases of gynecomastia with nonsteroidal antiandrogens including flutamide are mild to moderate.[35][36]
Gynecomastia: Pathology: A large glandular mass of male breast tissue, surgically removed
Pathology: A large glandular mass of male breast tissue, surgically removed
Gynecomastia: Microscopic image showing gynecomastoid hyperplasia, the cellular changes seen in gynecomastia H&E stain
Microscopic image showing gynecomastoid hyperplasia, the cellular changes seen in gynecomastia H&E stain

Worked examples

Example 1 — a first encounter with Gynecomastia

Start with the simplest possible case. Write down what Gynecomastia claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Gynecomastia before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Gynecomastia ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Gynecomastia

In research
Gynecomastia appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Gynecomastia in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Gynecomastia is common in secondary-school and first-year university syllabi. It links to neighbouring topics Andrology, Breast diseases, Endocrine diseases, so understanding it makes those chapters shorter.
In everyday life
Look for Gynecomastia outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Gynecomastia in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Gynecomastia means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Gynecomastia out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gynecomastia in simple terms?

Gynecomastia (also spelled gynaecomastia) is the non-cancerous enlargement of one or both breasts in men due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Physically speaking, gynecomastia is completely benign, but it is associated with significa…

Why does Gynecomastia matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Gynecomastia?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Gynecomastia.

Tags

  • Andrology
  • Breast diseases
  • Endocrine diseases
  • Medical conditions related to obesity
  • Men's health

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