Gigantomastia is a rare, noncancerous condition that causes excessive growth of the female breasts. The growth may occur in one or both breasts. The exact cause isn’t known.

Only a couple hundred cases of gigantomastia have been reported in the medical literature. The condition can occur randomly, but it has also been seen to occur during puberty, pregnancy, or after taking certain medications. It doesn’t occur in men.

The breast growth can occur over the course of a few years, but there have been some cases of gigantomastia where a woman’s breasts grew three or more cup sizes within a few days. Other symptoms include breast pain, posture problems, infections, and back pain.

While gigantomastia is considered a benign (noncancerous) condition, it can be physically disabling if not treated. In some cases, the condition resolves on its own, but many women with gigantomastia will need to have breast reduction surgery or a mastectomy.

Gigantomastia also goes by other names, including breast hypertrophy and macromastia.

The main symptom of gigantomastia is an excessive overgrowth of breast tissue in one breast (unilateral) or both breasts (bilateral). The growth may occur slowly over a period of a few years. In some women, the breast growth occurs rapidly over the course of just a few days or weeks.

There is no universally accepted definition for the amount of growth. Many researchers define gigantomastia as a breast enlargement that requires reduction of 1,000 to 2,000 grams per breast.

Other symptoms of gigantomastia include:

  • breast pain (mastalgia)
  • pain in the shoulders, back, and neck
  • redness, itchiness, and warmth on or underneath the breasts
  • poor posture
  • infections or abscesses
  • loss of nipple sensation

The pain and posture problems are usually caused by the excess weight of the breasts.

The exact mechanism by which gigantomastia occurs in the body isn’t well understood. Genetics and an increased sensitivity to female hormones, like prolactin or estrogen, are thought to play a role. For some women, gigantomastia happens spontaneously without an obvious cause.

Gigantomastia has been associated with:

Gigantomastia can be divided into several subtypes. The subtypes are related to the event that may have triggered the condition.

Types of gigantomastia include:

  • Gestational or pregnancy-induced gigantomastia occurs during pregnancy. This subtype is thought to be triggered by pregnancy hormones, usually during the first trimester. It occurs in just 1 out of every 100,000 pregnancies.
  • Puberty-induced or juvenile gigantomastia occurs during adolescence (between the ages of 11 and 19), likely because of sex hormones.
  • Medication- or drug-induced gigantomastia occurs after taking certain medications. Most commonly, it’s caused by a drug known as D-penicillamine, which is used to treat rheumatoid arthritis, Wilson’s disease, and cystinuria.
  • Idiopathic gigantomastia occurs spontaneously, with no obvious cause. This is the most common type of gigantomastia.

Your doctor will take a medical and family history and perform a physical examination. You may be asked questions about:

  • your breast size
  • other symptoms
  • the date of your first menstruation
  • any medications you’ve taken recently
  • if you could be pregnant

If you’re an adolescent, your doctor might make a diagnosis of gigantomastia if your breasts grew rapidly soon after your first menstrual period. Most of the time, other diagnostic tests aren’t needed unless your doctor suspects you have another underlying disorder.

There is no standard treatment for gigantomastia. The condition is usually treated on a case-by-case basis. Treatment is first aimed at treating any infections, ulcers, pain, and other complications. For example, antibiotics, warm dressings, and over-the-counter pain medications might be recommended.

Pregnancy-induced gigantomastia might go away on its own after giving birth. However, in most cases, surgery is considered to reduce the size of the breasts.


Surgery to reduce the size of the breasts is called breast reduction surgery. It’s also known as reduction mammoplasty. During a breast reduction surgery, a plastic surgeon will reduce the amount of breast tissue, remove excess skin, and reposition the nipple and the dark skin around it. The surgery takes a few hours. You may have to stay in the hospital for one night following the operation.

If you’re pregnant, you might have to wait until after finishing breastfeeding to have a breast reduction surgery. If you’re an adolescent, your doctor may want you to wait until after puberty is completed before you have the surgery. This is because there is high chance of reoccurrence. You may be asked to visit your doctor for an evaluation and physical examination every six months during this time.

Another type of surgery, known as mastectomy, has a much lower rate of reoccurrence. A mastectomy involves removing all of the breast tissue. After a mastectomy, you can get breast implants. However, mastectomy and implants may not be best treatment option due to the risk of complications. In addition, most women will not be able to breastfeed after a double mastectomy. Your doctor will discuss the risks and benefits of each type of surgery with you.


Your doctor might prescribe medications either before or after a breast reduction surgery to help stop the growth of the breasts. These may include:

  • tamoxifen, a selective estrogen receptor modulator (SERM) used in breast cancer treatment
  • medroxyprogesterone (Depo-Provera), also known as the birth control shot
  • bromocriptine, a dopaminergic receptor agonist often used for Parkinson’s disease that has been shown to stop breast growth
  • danazol, a drug typically used to treat endometriosis and the symptoms of fibrocystic breast disease in women

However, the effectiveness of these medications in treating gigantomastia varies. More research is needed.

The extreme breast enlargement and the excess weight of the breasts can result in physical complications, including:

  • over-stretching of the skin
  • skin rashes under the breasts
  • ulcers on the skin
  • neck, shoulder, and back pain
  • headaches
  • breast asymmetry (when one breast is larger than the other)
  • temporary or permanent nerve damage (specifically the fourth, fifth, or sixth intercostal nerves), resulting in loss of nipple sensation
  • difficulty playing sports or exercising, leading to obesity

In addition, extremely large breasts can result in psychological, emotional, and social problems. For example, teenagers with the condition may be harassed or embarrassed at school. This can lead to:

  • depression
  • anxiety
  • body image problems
  • avoidance of social activities

In pregnant women or women who have just given birth, gigantomastia can result in:

  • poor growth of the fetus
  • spontaneous abortion (miscarriage)
  • suppression of the milk supply
  • mastitis (breast infection)
  • blisters and wounds because the baby can’t latch on properly; the wounds can become painful or infected

If not treated, gigantomastia can lead to problems with posture and back problems, which can be physically disabling. It can also cause dangerous infections, body image issues, and pregnancy complications. In rare cases, a person with gigantomastia may need to have an emergency mastectomy because of complications. Gigantomastia doesn’t cause cancer and doesn’t spread to other parts of the body.

Breast reduction surgery is considered a safe and effective treatment. However, research has shown that puberty and pregnancy-induced gigantomastia may reoccur after breast reduction surgery. Mastectomy offers a more definitive treatment for gigantomastia.