[Nipple discharge: differential diagnostic considerations]

Each uni- or bilateral secretion of the nipple--spontaneous or easy to trigger--has to be examined thoroughly, independent of the colour or the amount of the secretion. Colours of the secretions do not refer to a specific breast disease. Main causes are functional disease with and without endogenous increase of prolactin secretion and benign and malignant breast diseases. Mastopathia, papilloma, fibroadenoma, nonpuerperal mastitis, and carcinoma of the breast are the most common pathological findings associated with secretions of the mammary gland.