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Nipple Discharge

by Mary Ann Kosir, MD

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 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.

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 mass

Mammary duct ectasia

Unilateral or often bilateral bloody (or guaiac-positive), serosanguinous, or multicolored (purulent, gray, or milky) discharge

Evaluation as for breast mass

Fibrocystic changes

A mass, often rubbery and tender, usually in premenopausal women

Possibly a history of other masses

Evaluation as for breast mass

Abscess or infection

Acute onset with pain, tenderness, or erythema

With abscess, a tender mass and possibly purulent discharge

Clinical evaluation

If discharge does not resolve with treatment, evaluation as for breast mass

Breast cancer

Most often, intraductal carcinoma or invasive ductal carcinoma

May have a palpable mass, skin changes, or lymphadenopathy

Sometimes bloody or guaiac-positive discharge

If suspected, evaluation as for breast mass

Hyperprolactinemia

Many causes (see Table: Causes of Hyperprolactinemia)

Often bilateral, milky not bloody discharge with multiple ducts involved and no masses

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 mass or pain is present.

Review of systems 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), H 2 -antagonists (eg, cimetidine, ranitidine), opioids, and dopamine D 2 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 and to identify any particular location associated with the 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 both breasts, 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. However, if the discharge is guaiac-positive, even if bilateral, cancer must be considered.

Presence of a breast mass, a bloody (or guaiac-positive) discharge, a spontaneous unilateral discharge, or history of an abnormality on a mammogram or an ultrasound scan requires follow-up with a surgeon who is experienced with breast disorders.

For other suggestive findings, see Some Causes of Nipple Discharge.

Testing

If endocrine causes are suspected, the following are measured:

  • 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 mass is done, usually beginning with

  • Ultrasonography

Lesions that appear cystic are sometimes aspirated, and solid masses 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, the following is done:

  • Mammography

Abnormal results are evaluated by biopsy guided by imaging. If mammography and ultrasonography do not identify a source and the discharge is spontaneous and comes from a single duct or breast, ductography (contrast-enhanced imaging of the milk duct) can be done.

Treatment

Treatment is based on the cause.

If the cause is benign and the discharge is persistent and annoying, the terminal duct can be excised on an outpatient basis.

Key Points

  • Nipple discharge is most often benign.

  • Bilateral, multiductal, guaiac-negative discharge is usually benign and has an endocrine etiology.

  • Spontaneous, unilateral discharge requires diagnostic testing; this type of discharge may be cancer, particularly if it is bloody (or guaiac-positive).

  • Presence of a breast mass, a bloody (or guaiac-positive) discharge, or history of an abnormality on a mammogram or an ultrasound scan requires follow-up with a surgeon who is experienced with breast disorders.

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