Updated December 30, 2014.

Gynecomastia refers to male breast enlargement, and occurs in about half of boys as they go through puberty. Although distressing to many teen boys who think that they are developing breasts, they should be reassured that gynecomastia is normal, common, and usually doesn't progress to the point that it is easily noticeable by their peers. And most importantly, in most cases, gynecomastia goes away without any treatment.

Symptoms

Most boys with gynecomastia will notice a small, firm, tender mass under one or both nipples. They may continue to grow a little at first, but they will then eventually flatten out again, often within a few months or years. The tenderness is also usually temporary.

Diagnosis

The diagnosis of gynecomastia is usually made based on a detailed physical exam (including a testicular exam) and the pattern of symptoms, especially the fact that your child is in puberty. A review of any medications that your child is taking will also be done. Testing, although not usually necessary in teen boys, might include:

• liver function tests
• plasma DHEAS or urinary 17-ketosteroids
• plasma estradiol
• plasma hCGá
• plasma LH and testosterone

Teens who are very overweight may have pseudogynecomastia, in which they have enlarged breasts because of increased fat and not true breast tissue. Unlike teens with true gynecomastia, pseudogynecomastia will not usually go away on its own unless the child loses weight.

Treatments

Although not usually necessary, if a teen boy has very large breasts or his gynecomastia isn't going away, then surgical treatment can be an option.

Most experts recommend waiting for at least two years before considering mastectomy for gynecomastia though.
Research is also being done on using anti-estrogen medications, such as raloxifen and tamoxifen, to treat persistent cases of gynecomastia. Other medications might include the aromatase inhibitor testolactone, and the weak androgen danazol.

Remember that the majority of teens don't require any treatment for their gynecomastia though.

What You Need To Know

• Gynecomastia usually goes away within two to three years in 90 percent of teens.
  
  
• An imbalance between estrogen and androgens, hormones that rise during puberty, is thought to cause gynecomastia.
  
  
• Gynecomastia is also sometimes associated with drug use, including marijuana and anabolic steroids.
  
  
• Gynecomastia is much less common before puberty, and these prepubertal boys should have a full endocrinological evaluation.
  
  
• Gynecomastia is also seen in children with Klinefelter syndrome, Kallmann syndrome, cirrhosis, thyroid disorders, testicular feminization, and hormone secreting tumors, and it can be a side effect of certain medications, such as cimetidine, human growth hormone, and spironolactone.
  
  
• Breast cancer is very rare in teen boys, so that would be an unlikely cause of breast swelling in teenagers. Still, boys should see their Pediatrician for an evaluation if they notice a lump in their breasts, both for an evaluation and for reassurance that they are okay.
  
  

References:

^{Breast disorders in the adolescent patient. Arca MJ - Adolesc Med Clin - 01-OCT-2004; 15(3): 473-85
Elective plastic surgical procedures in adolescence. McGrath MH - Adolesc Med Clin - 01-OCT-2004; 15(3): 487-502
Beneficial effects of raloxifene and tamoxifen in the treatment of pubertal gynecomastia. Lawrence SE - J Pediatr - 01-JUL-2004; 145(1): 71-6
Larsen: Williams Textbook of Endocrinology, 10th ed.,}