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| ICD9 = | OMIM = | MedlinePlus = 003165 | eMedicineSubj = med | eMedicineTopic = 934Gynecomastia, or gynaecomastia, is the development of abnormally large mammary glands in males resulting in breast enlargement, which can sometimes cause secretion of milk. The term comes from the Greek gyne meaning "woman" and mastos meaning "breast". The condition can occur physiologically in neonates, in adolescents, and in the elderly. In adolescent boys the condition is often a source of distress, but for the large majority of boys whose pubertal gynecomastia is not due to obesity, the breast development shrinks or disappears within a couple of years Adolescent gynecomastia. The causes of common gynecomastia remain uncertain, although it has generally been attributed to an imbalance of sex hormones or the tissue responsiveness to them; a root cause is rarely determined for individual cases. Breast prominence can result from hypertrophy of breast tissue, chest adipose tissue and skin, and is typically a combination. Breast prominence due solely to excessive adipose is often termed pseudogynecomastia or sometimes lipomastia.
Causes Physiologic gynecomastia occurs in neonates, at or before puberty and with aging. Many cases of gynecomastia are idiopathic, meaning they have no clear cause.
Potential pathologic causes of gynecomastia are: medications including hormones, increased serum estrogen, decreased testosterone production, androgen receptor defects, chronic kidney disease, chronic liver disease, HIV, and other chronic illness. Gynecomastia as a result of spinal cord injury and refeeding after starvation has been reported. In 25% of cases, the cause of the gynecomastia is not known.Medications cause 10-20% of cases of gynecomastia in post-adolescent adults. These include cimetidine, omeprazole, spironolactone, imatinib mesylate, finasteride and certain antipsychotics. Some act directly on the breast tissue, while others lead to increased secretion of prolactin from the pituitary by blocking the actions of dopamine (prolactin-inhibiting factor/PIF) on the lactotrope cell groups in the anterior pituitary. Androstenedione, used as a performance enhancing food supplement, can lead to breast enlargement by excess estrogen activity. Medications used in the treatment of prostate cancer, such as antiandrogens and GnRH analogs can also cause gynecomastia. Marijuana use is also thought by some to be a possible cause; however, published data is contradictory.Increased estrogen levels can also occur in certain testicular tumors, and in hyperthyroidism. Certain adrenal tumors cause elevated levels of androstenedione which is converted by the enzyme aromatase into estrone, a form of estrogen. Other tumors that secrete hCG can increase estrogen. A decrease in estrogen clearance can occur in liver disease, and this may be the mechanism of gynecomastia in liver cirrhosis. Obesity tends to increase estrogen levels.Decreased testosterone production can occur in congenital or acquired testicular failure, for example in genetic disorders such as Klinefelter Syndrome. Diseases of the hypothalamus or pituitary can also lead to low testosterone. Abuse of anabolic androgenic steroids (AAS) has a similar effect. Mutations to androgen receptors, such as those found in Kennedy disease can also cause gynecomastia.Although stopping these medications can lead to regression of the gynecomastia, surgery is sometimes necessary to eliminate the condition.Repeated topical application of products containing lavender and tea tree oils among other unidentified ingredients to three prepubescent males coincided with gynecomastia; it has been theorised that this could be due to their estrogenic and antiandrogenic activity. However, other circumstances around the study are not clear, and the sample size was insignificant so serious scientific conclusions cannot be drawn.
Diagnosis The condition usually can be diagnosed by examination by a physician. Occasionally, imaging by X-rays or ultrasound is needed to confirm the diagnosis. Blood tests are required to see if there is any underlying disease causing the gynecomastia.
Prognosis Gynecomastia is not physically harmful, but in some cases can be an indicator of other more dangerous underlying conditions. Growing glandular tissue, typically from some form of hormonal stimulation, is often tender or painful. Furthermore, it can frequently present social and psychological difficulties for the sufferer. Weight loss can alter the condition in cases where it is triggered by obesity, but losing weight will not reduce the glandular component and patients cannot target areas for weight loss. Massive weight loss can result in sagging tissues about the chest, chest ptosis, or drooping chest.
Treatment Treating the underlying cause of the gynecomastia may lead to improvement in the condition. Patients should talk with their doctor about revising any medications that are found to be causing gynecomastia; often, an alternative medication can be found that avoids gynecomastia side-effects, while still treating the primary condition for which the original medication was found not to be suitable due to causing gynecomastia side-effects (e.g., in place of taking spironolactone the alternative eplerenone can be used.) Selective estrogen receptor modulator medications, such as tamoxifen and clomiphene, or androgens or aromatase inhibitors such as Letrozole are medical treatment options, although they are not universally approved for the treatment of gynecomastia. Endocrinological attention may help during the first 2-3 years. After that window, however, the breast tissue tends to remain and harden, leaving surgery (either liposuction, gland excision, skin sculpture, reduction mammoplasty, or a combination of these surgical techniques) the only treatment option. Many American insurance companies deny coverage for surgery for gynecomastia treatment on the grounds that it is a cosmetic procedure. Radiation therapy is sometimes used to prevent gynecomastia in patients with prostate cancer prior to estrogen therapy. Compression garments can camouflage chest deformity and stabilize bouncing tissue bringing emotional relief to some. There are also those who choose to live with the condition.
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