What causes milky nipple discharge and how is it treated?

Milky Nipple Discharge: Causes and Treatment

Milky nipple discharge is typically physiologic in nature and does not require further radiologic investigation if routine screening mammography is up to date. 1

Characterization of Milky Nipple Discharge

• Milky nipple discharge is classified as physiologic when it is bilateral, originates from multiple ducts, and occurs only when provoked (non-spontaneous) 2
• Physiologic discharge is typically white, green, yellow, or milky in appearance 1
• Many studies have shown physiologic nipple discharge to be benign, with no association with in situ or invasive cancer 1, 2
• Milky discharge is distinct from pathologic discharge, which is typically spontaneous, unilateral, from a single duct, and bloody or serous in appearance 1, 2

Common Causes of Milky Nipple Discharge

• Hyperprolactinemia is a common cause of milky discharge (galactorrhea), which can be due to:
  • Medications (particularly antipsychotics) 3
  • Pituitary tumors 4, 3
  • Endocrine disorders 3
• Duct ectasia is another common benign cause (17%-36% of cases) of nipple discharge 2
• Physiologic hormonal changes, particularly during reproductive years 5
• Up to 50% of women in their reproductive years can express one or more drops of fluid from the breast 5

Evaluation Approach

• Determine if the discharge is physiologic or pathologic based on:
  • Laterality (bilateral vs. unilateral) 2
  • Number of ducts involved (multiple vs. single) 2
  • Color (milky/white/green/yellow vs. bloody/serous) 2
  • Spontaneity (provoked vs. spontaneous) 2
• Assess for associated breast mass (absence of mass is reassuring) 2
• For bilateral, non-spontaneous, milky discharge:
  • No radiologic investigation is needed if routine screening mammography is up to date 1
  • Imaging is generally not required, especially in young women 2

Treatment Recommendations

• For physiologic milky discharge:
  • Patient education to stop compression/manipulation of the breast 2
  • Observation is recommended, especially in younger women 2
  • If discharge is due to medication-induced hyperprolactinemia, consider medication adjustment if possible 3
  • For persistent galactorrhea due to hyperprolactinemia without identifiable cause, bromocriptine may be considered 4

When to Consider Further Evaluation

• Development of spontaneous discharge 2
• Change in discharge characteristics (becomes bloody or serous) 2
• Development of a palpable mass 2
• Discharge becomes unilateral or from a single duct 2
• If discharge persists despite stopping breast compression, re-evaluation in 3-6 months is recommended 2

Important Caveats

• Milky discharge in males is rare but has a strong association with underlying malignancy (57% in one study) and warrants thorough evaluation 1
• The risk of malignancy increases with age in patients with pathologic nipple discharge 1
• Even with physiologic discharge, instruct patients to report development of any spontaneous discharge, which would warrant further evaluation 2
• Surgical intervention is typically not indicated for physiologic milky discharge 6, 4