by Chaire Lis, MD and Nina Capiro, MD

Nipple discharge is the third leading breast complaint after lumps and pain, with a prevalence of 5-10% in women. Nipple discharge can be categorized as follows: galactorrhea, discharge in pregnant women, purulent discharge, multiple pore discharge, and single or pauci-pore discharge. Galactorrhea is milky discharge in post-partum women, is usually bilateral and/or multiple pore. Discharge in pregnant women typically occurs in the second trimester of pregnancy, can be unilateral or bilateral, occasionally bloody. Purulent discharge is associated with infection. Multiple pore discharge can be yellow, green, or multicolored and is associated with galactophore duct ectasia, fibrocystic disease, or periductal mastitis. Single or pauci-pore discharge, is often spontaneous, serous or bloody and is associated with pathology. Characteristics of suspicious nipple discharge include unilateral/single pore, spontaneous, persistent, and clear, serous or bloody discharge. Any nipple discharge with an associated palpable abnormality or new nipple inversion should be considered suspicious.

Nipple discharge in women is usually due to benign pathologies including ductal ectasia in 6-59% of cases, and papillomas in 35-56% of cases. Papillomas resulting in nipple discharge are often excised, and surgical excision of papillomas with atypical features have an upgrade rate of malignancy on excision of 21-38%. Nipple discharge is associated with a 5-23% risk of malignancy in women, typically DCIS. Any discharge in a man is suspicious and associated with breast cancer in 25-57% of cases. Mammography and ultrasound should be used as first line imaging modalities in evaluating suspicious nipple discharge. MRI can be used if mammography and ultrasound are negative.

Mammography should always be used as the first line examination for evaluation of suspicious nipple discharge, however sensitivity is relatively low (20-25%). Low sensitivity of mammography is due to the fact that lesions are usually small, retroareolar, intraductal, and/or non-calcified. Specific attention should be paid to the retroareolar region with localized compression or magnification views. Possible mammographic findings include retroareolar eggshell calcifications (associated with papillomas), rod-like calcifications (associated with duct ectasia), and suspicious calcifications which may indicate underlying malignancy such as DCIS.

Ultrasound should always be obtained for evaluation of suspicious nipple discharge, and is relatively sensitive and specific when compared to mammography (56% and 75% respectively). Heated gel and warm ambient room temperature should be used to prevent nipple muscle contraction. Technical maneuvers include tilting the transducer to view the axis of the duct, with peripheral compression to improve visualization of the nipple and subareolar regions. Ductal ectasia, defined as a diameter >3mm, is one of the most common findings. Ductal ectasia which is peripheral, with irregular ductal margins, thickening of the wall, and hypoechoic adjacent tissues are suggestive of malignancy. Intraductal masses can also be visualized, and Doppler should be used to differentiate ductal secretions from intraductal nodules/masses.

MRI with contrast is very sensitive and with a high negative predictive value, however there is a high false positive rate. Non-mass enhancement is the most common finding in patients with suspicious nipple discharge. In a study which evaluated 47 patients with suspicious nipple discharge, 59% of malignant lesions demonstrated non-mass enhancement with segmental distribution. A focus of enhancement is also considered suspicious in these patients, as it may suggest a papilloma. High T1 signal intensity within ducts suggest proteinaceous/hemorrhagic debris.

Galactography or ductography had previously been considered the gold standard for evaluation of nipple discharge, however in recent years this modality is falling out of favor, as there are several disadvantages, such as difficulty with duct catheterization resulting in procedure failure, and procedural risks including contrast extravasation, iodinated contrast allergy, and mastitis. In addition, ductography cannot differentiate malignant from benign lesions. More recent studies show that MRI is much more sensitive than ductography (98% for MRI, versus 49% for ductography). Another advantage of MRI is that it evaluates more of the breast parenchyma, however this may also be considered a disadvantage as it results in a high false positive rate.


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