Nipple discharge in non-lactating women can be classified as either galactorrhea or non-milky nipple discharge. Galactorrhea is usually caused by hyperprolactinemia and is associated with endocrine disorders or medication. Most of the causes of non-milky nipple discharge are benign, with less than 15% of cases related to cancer. The diagnostic approach is based on patient history and the characteristics of the discharge. Spontaneous, unilateral, and/or bloody nipple discharge, especially in women older than 40 years, should raise suspicion of malignancy. Treatment depends on the underlying disorder.
Physiological nipple discharge
- Definition: bilateral nipple discharge, typically milky
- Galactorrhea: milk production in non-breastfeeding women or men ; 
- Chronic nipple stimulation; (e.g., piercings; , tight clothing, etc.)
Pathological nipple discharge
- Features that should raise concern for malignancy
|Physiological nipple discharge|
|Pathological nipple discharge|
- Non-milky nipple discharge: : Treatment depends on the underlying disorder and can be found under respective causes (e.g., terminal ductal excision in the case of intraductal papilloma).