Nipple Discharge: A Merck Manual of Patient Symptoms podcast

Nipple discharge is a common complaint in women who are not pregnant or breastfeeding, especially during the reproductive years. Nipple discharge is not necessarily abnormal, even among postmenopausal women, although it is always abnormal in men.

Nipple discharge can be serous (yellow), mucinous (clear and watery), milky, sanguineous (bloody), purulent, multicolored and sticky, or serosanguineous (pink). It may occur spontaneously or only in response to breast manipulation.

Pathophysiology

Nipple discharge may be breast milk or an exudate produced by a number of conditions.

Breast milk production in nonpregnant and nonlactating women (galactorrhea) typically involves an elevated prolactin level, which stimulates glandular tissue of the breast. However, only some patients with elevated prolactin levels develop galactorrhea.

Etiology

Most frequently, nipple discharge has a benign cause (see Table 1: Breast Disorders: Some Causes of Nipple Discharge). Cancer (usually intraductal carcinoma or invasive ductal carcinoma) causes < 10% of cases. The rest result from benign ductal disorders (eg, intraductal papilloma, mammary duct ectasia, fibrocystic changes), endocrine disorders, or breast abscesses or infections. Of these causes, intraductal papilloma is probably the most common; it is also the most common cause of a bloody nipple discharge without a breast mass.

Endocrine causes involve elevation of prolactin levels, which has numerous causes.

Table 1
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Some Causes of Nipple Discharge Cause Suggestive Findings Diagnostic Approach Benign breast disorders Intraductal papilloma (most common cause) Unilateral bloody (or guaiac-positive) or serosanguinous discharge Evaluation as for breast lump Mammary duct ectasia Unilateral or often bilateral bloody (or guaiac-positive), serosanguinous, or multicolored (purulent, gray, or milky) discharge Evaluation as for breast lump Fibrocystic changes Lump, often rubbery and tender, usually in premenopausal women Possibly a history of other lumps Evaluation as for breast lump Abscess or infection Acute onset with pain, tenderness, or erythema With abscess, a tender lump and possibly purulent discharge Clinical evaluation If discharge does not resolve with treatment, evaluation as for breast lump Breast cancer Most often, intraductal carcinoma or invasive ductal carcinoma May have a palpable lump, skin changes, or lymphadenopathy Sometimes bloody or guaiac-positive discharge If suspected, evaluation as for breast lump Hyperprolactinemia Many causes (see Table 3: Pituitary Disorders: Causes of Hyperprolactinemia) Often bilateral, milky not bloody discharge with multiple ducts involved and no lumps Possibly menstrual irregularities or amenorrhea If a pituitary lesion is the cause, possibly signs of CNS mass (visual field changes, headache) or other endocrinopathy Prolactin level, TSH, review of drug use If prolactin or TSH is elevated, MRI of head TSH = thyroid-stimulating hormone.

Evaluation

History

History of present illness should include whether the current discharge is unilateral or bilateral, what its color is, how long it has lasted, whether it is spontaneous or occurs only with nipple stimulation, and whether a lump or pain is present.

Review of symptoms should seek symptoms suggesting possible causes, including fever (mastitis or breast abscess); cold intolerance, constipation, or weight gain (hypothyroidism); amenorrhea, infertility, headache, or visual disturbances (pituitary tumor); and ascites or jaundice (liver disorders).

Past medical history should include possible causes of hyperprolactinemia, including chronic renal failure, pregnancy, liver disorders, and thyroid disorders, as well as history of infertility, hypertension, depression, breastfeeding, menstrual patterns, and cancer. Clinicians should ask specifically about drugs that can cause prolactin release such as oral contraceptives, antihypertensive drugs (eg, methyldopa, reserpine, verapamil), H₂-antagonists (eg, cimetidine, ranitidine), opioids, and dopamine D₂ antagonists (eg, many psychoactive drugs, including phenothiazines and tricyclic antidepressants).

Physical examination

Physical examination focuses on the breasts. The breasts are inspected for symmetry, dimpling of the skin, erythema, swelling, color changes in the nipple and skin, and crusting, ulceration, or retraction of the nipple. The breasts are palpated for masses and evidence of lymphadenopathy in the axillary or supraclavicular region. If there is no spontaneous discharge, the area around the nipples is systematically palpated to try to stimulate a discharge. A bright light and magnifying lens can help assess whether the nipple discharge is uniductal or multiductal.

Red flags

Certain findings are of particular concern:

• Spontaneous discharge
• Age ≥ 40
• Unilateral discharge
• Bloody or guaiac-positive discharge
• Palpable mass
• Male sex

Interpretation of findings

Important differentiating points are whether a mass is present, whether the discharge involves one or multiple ducts (either one or more ducts in both breasts or more than one duct in one breast), and whether the discharge is bloody (including guaiac-positive).

If a mass is present, cancer must be considered. Because cancer rarely involves both breasts or multiple ducts at presentation, a bilateral, guaiac-negative discharge suggests an endocrine cause, as does unilateral, multiductal discharge. However, if the discharge is guaiac-positive or involves only one duct, cancer must be considered.

For other suggestive findings, see Table 1: Breast Disorders: Some Causes of Nipple Discharge.

Testing

If endocrine causes are suspected, the following are done:

• Prolactin level
• Thyroid-stimulating hormone (TSH) level

If discharge is guaiac-positive, the following is done:

• Cytology

If there is a palpable mass, evaluation as for breast lump, usually beginning with

• Ultrasonography

Lesions that appear cystic are sometimes aspirated, and solid lumps or any that remain after aspiration are evaluated with mammography followed by imaging-guided biopsy.

If there is no mass but cancer is otherwise suspected or if other tests are indeterminate,

• Mammography

Abnormal results are evaluated by imaging-guided biopsy. If no lump is palpable and mammogram is normal, cancer is highly unlikely.

Treatment

Treatment is based on the cause.

If the cause is benign and the discharge is persistent and annoying, a nipple-flap duct resection, usually done as an outpatient procedure using a local anesthetic, can eliminate the discharge and relieve the patient's anxiety.

Key Points

• Nipple discharge is most often benign.
• Bilateral, multiductal, guaiac-negative discharge is usually benign and has an endocrine etiology.
• Unilateral, uniductal, bloody (or guaiac-positive) discharge could be cancer, especially in patients ≥ 40.
• Presence of a breast mass, a bloody (or guaiac-positive) discharge, or history of an abnormal mammogram or abnormal ultrasound requires follow-up with a surgical clinician who is experienced with breast disorders.

Last full review/revision November 2008 by Victor G. Vogel, MD, MHS