Nipple discharge is a common symptom experienced by 50 to 80% of women at least once in their lives. Fortunately, most cases are benign conditions or normal physiological responses unrelated to breast cancer. What the Donguibogam describes as 'heat accumulated in the heart and spleen' can be understood in modern medicine as stress hormone imbalances, inflammatory reactions, and cellular changes within the lactiferous ducts. Nipple discharge can be broadly divided into two categories. The first is physiological discharge. Even outside of pregnancy or breastfeeding, stimulation of the nipple or friction from clothing can produce a small amount of milky, transparent, or clear discharge from both breasts. This is a natural physical reaction, so there is no need for undue concern. The second is pathological discharge, which typically appears from only one breast and often looks bloody red, brown, dark green, or purulent. One common cause is duct ectasia. In duct ectasia, the lactiferous ducts beneath the nipple become dilated and inflamed, which can lead to sticky green, brown, or even black discharge. This occurs mainly in women during perimenopause, though it can also affect younger women. Another benign cause is intraductal papilloma, a small benign tumor that develops inside a lactiferous duct and can cause bloody discharge. Hormonal imbalance can also cause nipple discharge. In particular, when levels of prolactin, the milk-stimulating hormone, increase due to pituitary gland issues, a milky discharge can appear even without pregnancy or nursing; thyroid gland dysfunction can also play a role. Certain medications, such as antidepressants, hypertension medications, and oral contraceptives, can induce nipple discharge as well. Although rare, discharge can be a sign of breast cancer. Therefore, if it comes from only one breast, contains blood, flows persistently without stimulation, or is accompanied by suspicious symptoms like a palpable lump, it is essential to consult a breast specialist to identify the precise cause. A physician will evaluate the nature, color, and frequency of the discharge, making an accurate diagnosis using mammography, breast ultrasound, and, if needed, ductography or biopsy. Most cases turn out to be benign conditions, but having an early evaluation remains the most important step.
