Nipple discharge is the release of fluid from the nipples of the breasts. For women who aren't breastfeeding, the sight of nipple discharge can be alarming. But if you notice discharge from your nipple, there's no reason to panic. While nipple discharge can be serious, in most cases, it's either normal or due to a minor condition.

Abnormal nipple discharge may be described as any discharge not associated with lactation. The nature of the discharge may range in color, consistency and composition, and occur in one or both breasts. Although it is considered normal in a wide variety of circumstances it is the third major reason involving the breasts for which women seek medical attention, after breast lumps and breast pain.

It is also known to occur in adolescent boys and girls going through puberty. Men are also subject to nipple discharge, which is significantly more unusual and requires a doctor's follow-up. About 3% of cases of discharge are due to cancer. Nipple discharge can vary in a number of different ways, and some of these can give clues to the possible underlying causes.  

 Types of discharge.

Examples of some of the most common types of nipple discharge include:

Milky discharge: This is the most common type of nipple discharge. In women, this can be because the woman has recently stopped breast-feeding or due to hormonal shifts in a premenopausal woman.

Bloody discharge: Blood discharge can be caused by a non-cancerous tumor called a papilloma, which can irritate the tissue inside a breast duct. In rare instances, bloody discharge can be due to breast cancer.

Clear discharge: Clear discharge from one breast only can be a symptom of breast cancer. Clear discharge from both breasts is usually less concerning, but if a woman is concerned, she should visit her doctor.

Green-tinged nipple discharge: Discharge of this color can be a symptom of a cyst underneath the nipple or areola that is draining.

Timing. The most common causes of nipple discharge vary depending on whether a woman is premenopausal or postmenopausal, and if she is pregnant, breastfeeding, or has given birth in the past. Most nipple discharge occurs in women who are premenopausal, especially women in the most fertile years.

Unilateral vs Bilateral. Nipple discharge may occur on one side (unilateral) or on both sides (bilateral). Unilateral discharge is more likely to be related to an underlying conditions such as a papilloma, ectasia, or even cancer, whereas bilateral discharge is more likely related to hormonal changes or systemic (system wide) conditions such as thyroid disease.

Single vs Multiple Ducts. Discharge may occur from a single breast duct or instead occur from multiple ducts. Again, discharge from a single duct is more likely to be due to a local condition affecting the breast.

Consistency Nipple discharge may be thin and clear, slightly thicker and milky, purulent (pus-like) and cloudy (with infections), or very thick, sticky, and cheese-like (with conditions such as blocked milk ducts or ectasia).

Color. The color of breast discharge is also very important when it comes to determining underlying causes. Colors may include:

Clear or "serous" with duct ectasia and cancer

Milky, such as in women who are breastfeeding, hormone-related causes, and with galactorrhea (see below) in women, men, or even infants.

Yellow, often related to an infection.

Green, commonly seen with fibrocystic disease.

Brown, often with fibrocystic disease or mammary duct ectasia.

Bloody: Bloody discharge may be a sign of breast cancer but is more likely to be due to another condition such as an intraductal papilloma.                         

Causes of nipple discharge.

It's thought that 50 to 80 percent of women have at least a drop or two of discharge at some points in their lives, and there are many potential causes. Most often, these causes are benign, though roughly 7 percent to 15 percent of women who have discharge significant enough to visit their doctor are found to have breast cancer.              

Causes of normal nipple discharge.

Some causes of normal nipple discharge include:

Pregnancy. In the early stages of pregnancy, some women notice clear breast discharge coming from their nipples. In the later stages of pregnancy, this discharge may take on a watery, milky appearance.

Stopping breastfeeding. Even after you have stopped nursing your baby, you may notice that a milk-like breast discharge persists for a while.

Stimulation/Local Irritation.  Nipples may secrete fluid when they are stimulated or squeezed. Normal nipple discharge may also occur when your nipples are repeatedly irritated by rough clothing or an improperly fitting bra or during vigorous physical exercise, such as jogging.

Causes of abnormal nipple discharge.

Possible causes of abnormal discharge include:

Fibrocystic breast changes. Fibrocystic refers to the presence or development of fibrous tissue and cysts. Fibrocystic changes in your breasts may cause lumps or thickenings in your breast tissue. They do not indicate, though, the presence of cancer. In addition to causing pain and itching, fibrocystic breast changes can, at times, cause secretion of clear, white, yellow, or green nipple discharge. Premenopausal women who have fibrocystic breasts may have breast discharge before their periods. Symptoms may include breast pain, lumpy breasts, and a yellow-green or brown discharge.

Galactorrhea/Hyperprolactinemia

A milky discharge, similar to that seen in women who are breastfeeding, may occur in women who aren't breastfeeding, men, or even young children, and is referred to as galactorrhea. It is most often due to an increased level of the hormone prolactin in the blood (a hormone secreted by the pituitary gland that is involved with breast development and breastfeeding), in a condition referred to as hyperprolactinemia. In women, hyperprolactinemia is often accompanied by amenorrhea (lack of menstrual periods), but in men, nipple discharge may be the first symptoms.

There are a number of potential causes of elevated prolactin levels, including:

Medications: Drugs known to elevate prolactin levels include some high blood pressure medications, opioids, some antidepressants, antipsychotics, and some drugs used for acid reflux. Galactorrhea is not a disease and has many possible causes. These include: Pituitary gland tumors, certain medications, including some hormones and psychotropic drug, hormonal therapies such as birth control pills and sedatives.

Infection. Nipple discharge that contains pus may indicate an infection in your breast. This is also known as mastitis. Mastitis is usually seen in women who are breastfeeding. But it can develop in women who are not lactating. If you have an infection or abscess in your breast, you may also notice that your breast is sore, red, or warm to the touch.

Mammary duct ectasia (Dilated Milk Ducts). This is the second most common cause of abnormal nipple discharge. It is typically seen in women who are approaching menopause or after menopause. This condition results in inflammation and possible blockage of ducts located underneath the nipple. When this occurs, an infection may develop that results in thick, greenish nipple discharge. The discharge can also be brown, or even black, and very thick and cheese-like. It is often accompanied by nipple tenderness and redness. It may lead to a secondary bacterial infection (mastitis) and can also cause the nipples to turn inwards (nipple inversion) raising concern about breast cancer. It usually goes away in time, with relief provided by hot packs, but sometimes requires surgical treatment.

Intraductal papilloma. These are noncancerous growths in the ducts of the breast. They are the most common reasons women experience abnormal nipple discharge. When they become inflamed, intraductalpapillomas may result in nipple discharge that contains blood or is sticky in texture.

Breast Cancer and Carcinoma in Situ

While breast cancer is not a common cause of nipple discharge, it can be an early warning sign of breast cancer that is still in the preinvasive stage (ductal carcinoma in situ), especially when it occurs in a woman over the age of 40, is associated with a breast mass, is bloody, unilateral, or involves only one duct.

Though nipple discharge related to breast cancer is often thought to be bloody, this is not necessarily the case, and the discharge may be clear or milky.

Nipple Discharge in Men

When men develop nipple discharge, there is often an underlying problem. An investigation looking for conditions such as an elevated prolactin level is important, but it's also very important to note that men can get breast cancer too, and male breast cancer is often under-recognized, even among physicians . Some other common causes of male nipple discharge include: Testosterone deficiency, gynecomastia, a condition that causes breast enlargement or tenderness, pituitary tumor, this is because the pituitary gland is responsible for releasing hormones that cause milk production in the nipples and cancer of the breast.

Nipple Discharge in Infants

Small amounts of clear to milky nipple discharge (and often some breast swelling or a small lump) in newborns is fairly common, related to hormones left over from pregnancy. Later in infancy, bloody discharge may occur with the most common cause being mammary duct ectasia.

Diagnosis.

 

Seeing a doctor for nipple discharge is always advised, especially if other symptoms are present, such as changes in breast size or shape, a palpable lump in the breast, discharge from only one breast, blood-tinged discharge, discharge that continues over the course of several days and swelling under the armpit or around the collar bone that may be associated with breast cancer. Possible tests may include:

Cytology. A sample of the discharge may be evaluated under the microscope in the lab (cytology) to observe the cells present. While this test may show cancer cells, a negative cytology exam can't rule out cancer.

Ultrasound. An ultrasound examination is a common test to look for abnormalities in the area behind nipple and areola. Other test are: Ductogram/Galactogram, serum prolactin level, mammogram, thyroid test (TSH), brain MRI or CT and biopsy.

 What are the treatment options?

The treatment options depend on the cause and type of the discharge.

Initially, an evaluation of malignancy is always indicated. If no abnormality is found, then a surgical duct excision may resolve the symptoms. Treatment also depends on whether single-duct or multiple-duct discharge is present, and whether the symptoms of nipple discharge are distressing to the patient.