Evaluation of Nipple Discharge

Introduction to Nipple Discharge

The American College of Radiology recommends differentiating between physiologic and pathologic discharge, with no imaging needed for physiologic discharge, while pathologic discharge requires mammography/DBT and ultrasound as first-line imaging modalities 1, 2

Physiologic discharge is bilateral, originates from multiple ducts, is white, green, or yellow in color, occurs only when provoked, and has no association with breast cancer 1, 3
Pathologic discharge is spontaneous, from a single duct orifice, unilateral, serous or bloody, and associated with underlying malignancy in 3-29% of cases 1, 3

For women ≥40 years or men ≥25 years, initial imaging should be mammography or digital breast tomosynthesis (DBT), with a sensitivity for malignancy of 15-68% and specificity of 38-98% 2, 3, 4
Complementary ultrasound is more sensitive than mammography but has lower specificity, and is useful for identifying intraductal lesions 5, 4

When initial imaging is negative, MRI may be considered, with an overall sensitivity of up to 96%, providing physiologic information in addition to morphologic detail 4, 6
Ductography (galactography) is historically used for identifying intraductal lesions, but is invasive and may cause discomfort/pain, with a technical failure rate of 10-15% 4, 6

Image-guided core needle biopsy (CNB) is preferred over fine-needle aspiration (FNA), with superior sensitivity, specificity, and correct histologic grading 7

Benign intraductal papilloma is the most common cause of pathologic nipple discharge (35-48%), with mammographic findings including asymmetrically dilated ducts, circumscribed subareolar mass, or grouped microcalcifications 1, 3, 4
Ductal ectasia is the second most common cause (17-36%) 1
Malignancy is less common but important to exclude, with a higher risk in men (23-57% of nipple discharge cases are malignant) 1, 4

A negative mammogram reduces the risk of carcinoma to 3%, while a negative mammogram and ultrasound reduce the risk to approximately 0% 3
False-positive ultrasound results may occur due to volume averaging with ductal wall in tortuous ducts, intraductal and periductal fibrosis, or adherent blood clots or inspissated secretions 4

For women ≥40 years, the American College of Radiology recommends diagnostic mammography or digital breast tomosynthesis (DBT) as the initial study, with complementary ultrasound of both breasts, and repeat mammography if prior study was >6 months ago, with a rated appropriateness of 9/9 8, 9
For women 30-39 years, either mammography/DBT or ultrasound can serve as the initial examination, with the complementary modality added regardless of which is performed first, both rated 9/9 8, 9
For women <30 years, ultrasound should be the initial and primary examination, rated 9/9, with mammography/DBT added only if ultrasound shows suspicious findings, due to low cancer incidence and theoretical radiation risk 8, 9
For men ≥25 years, initial mammography/DBT with complementary ultrasound is recommended, rated 8-9/9, due to substantially higher malignancy risk 8, 9
For men <25 years, initial ultrasound is recommended, rated 9/9, with mammography added as indicated 8, 9