Nipple discharge is the third most common breast complaint for which women seek medical attention, after lumps and breast pain. A woman's breasts secret some fluid throughout most of the adult life. The difference between lactating (milk producing) and non-lactating breasts is mainly in the degree or amount of secretion and to a smaller degree the chemical composition of the fluid. In non-lactating women, small plugs of tissue block the nipple ducts and keep the nipple from discharging fluid. Nipple discharge are often yellow, green, brown, bloody, or milky in appearance.

Importantly, most nipple discharges, while often bothersome, are not cancerous. However, any woman with a suspicious or worrisome nipple discharge (see below) should consult her physician.

Nipple Discharge is of Concern if it is:

1. bloody or watery (serous) with a red, pink, or brown color
2. sticky and clear in color or brown to black in color (opalescent)
3. appears spontaneously without squeezing the nipple
4. persistent
5. on one side only (unilateral)
6. a fluid other than breast milk

Causes of Nipple Discharge

Milky discharge (cloudy, whitish or almost clear in color, thin, non-sticky) is the most common type of discharge. Most milky discharge is caused by lactation or increased mechanical stimulation of the nipple due to fondling, suckling or irritation from clothing during exercise or activity. Drugs or hormones that stimulate prolactin secretion can cause spontaneous, persistent production of milk (galactorrhea). Prolactin is the hormone produced by the pituitary gland that starts the growth of the mammary glands and triggers production of milk. Some pituitary tumors cause excess prolactin secretion that can lead to milky nipple discharge, usually from both breasts (bilateral).  Opalescent discharge that is yellow or green in color is normal.

Most bloody or watery (serous) nipple discharge (approximately 90%) is due to a benign condition such as papilloma or infection. A papilloma is a non-cancerous, wart-like tumor with a branching or stalk that has grown inside the breast duct. Papillomas frequently involve the large milk ducts near the nipple. Multiple papillomas may also be found in the small breast ducts further from the nipple.

Of the benign conditions that cause suspicious nipple discharge, approximately half is due to papilloma and the other half is a mixture of benign conditions such as fibrocystic conditions (i.e., lumpy) or duct ectasia (widening and hardening of the duct due to age or damage). For example, women with fibrocystic breasts may experience clear, yellow or light green discharge. Most opalescent discharge is due to duct ectasia or cyst.

Suspicious nipple discharge is due to cancer in about 10% of cases. That means, the vast majority nipple discharges are noncancerous. Discharge caused by a malignant condition is commonly on one side only. However, papillomas usually causes discharge from a single breast duct, so certainly not all unilateral discharges are associated with cancer. Nipple discharge can also be associated with a rare form of cancer called Paget's disease of the nipple.

Signs of Paget's disease usually only occur on one nipple and may include:

• persistent crustiness, scaliness, or redness of the nipple
• itching or burning of the nipple and surrounding areola
• bleeding or oozing from the nipple and areola

Nipple Discharge in Men

Both male and female adolescents may experience a milky discharge during puberty. Nipple discharge in the adult male is more often associated with a malignant condition than in the female. Mammography should be performed and biopsy should be performed if a mass or mammographic abnormality is found.

Bloody Discharge During Pregnancy and Lactation

Bloody discharge during pregnancy/lactation is fairly common and usually not related to papilloma. During pregnancy and lactation, breast tissue grows rapidly and this can lead to duct irritation that causes bloody nipple discharge or pus. The breasts may also become swollen and warm. This discharge should not interfere with nursing. If the discharge persists after lactation has stopped, it should be evaluated further.

Examination for Nipple Discharge

Women should report any suspicious nipple discharge to their physicians. A blood test of prolactin levels is often made to determine hormonal causes of excessive milky discharge (galactorrhea). A hormone imbalance, pituitary tumor, and certain drugs such as sedatives, tranquilizers, hormone replacement or birth control pills may cause excessive prolactin levels.

If there is a suspicious nipple discharge (see above criteria), an examination by a physician should be performed. Clinical breast exam (CBE) is first performed. If a discharge can be produced during the examination, some of the fluid may be collected and examined under a microscope to see if any blood cells or cancer cells are present. This test is called a nipple smear. The discharge may also be examined for signs of infection such as pus. Papillomas may be seen with microscopic examination of a nipple discharge, but this test may be inconclusive.

If the discharge is bloody or serous, a mammogram is often the first test to be performed. Even when no cancer cells are found in a nipple discharge, it is not possible to rule out breast cancer or other condition such as papilloma.

If a patient has a suspicious mass together with nipple discharge, evaluation of the mass should be performed using mammography, adjunctive imaging and biopsy as necessary. If these tests are negative and show no malignancy, nipple smear should be evaluated.

Some papillomas are near the nipple and are large enough to be felt. In these cases, a needle biopsy can be done to test for malignancy or diagnose papilloma.

In some cases, a galactogram (also called a ductogram) is performed to aid in diagnosing the cause of an abnormal nipple discharge such as intraductal papilloma. However, a ductogram that does not show an abnormality does not exclude the fact that a significant lesion may be present.

Treatment for Persistent Nipple Discharge

The standard treatment for nipple discharge that has no hormonal involvement is duct excision. Duct excision is usually performed on an outpatient basis with local anesthesia. The procedure is usually done through a small circular incision near the areolar border around the nipple. It is not uncommon for the pathology found to be so microscopic that it is invisible without the assistance of a microscope. Typically, nursing ability and nipple sensation are preserved after duct excision. Breast-feeding in the other breast should have no affect from the duct excision in the opposite breast.

There is usually not a significant change in breast size/shape after duct excision since only a small amount of tissue is removed. There is no evidence of increased future risk of breast cancer from the procedure. Some suggest that there may be a slight increase in risk of breast cancer for patients with a papilloma, but this possibly higher risk has nothing to do with the treatment chosen.

Conclusion:

The above information and statistics are general guidelines. If you have nipple discharge that is worrisome, please do not hesitate to contact your physician or healthcare provider about it. However, keep in mind that most nipple discharge is not caused by breast cancer.

Additional References and Resources:

• The Mayo Clinic provides information about nipple discharge, http://www.mayoclinic.com/
• Lois F. O'Grady, MD, et al., A Practical Approach to Breast Disease, Boston: Little, Brown and Company, 1995, pp. 131-139.

Updated: March 18, 2008

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