to be abnormal (pathological) if it is crystal clear or blood-stained, is from only one breast, or is associated with a breast lump, swelling, redness or overlying skin changes. A blocked or enlarged milk duct can result in nipple discharge. Intraductal papillomas are non-cancerous lesions and commonest in women age 30 to 50. Divided into central and peripheral papillomas, nipple discharge is more frequently observed when they are central. Up to half of women with intraductal papillomas may present with bloody nipple discharge, but it can also be straw-coloured. They are usually too small to feel and have a rare association with breast cancer. 15-20% of people with nipple discharge are found to have duct ectasia. This is usually in perimenopausal and menopausal women, who may have associated pain and retraction of the nipple. A lump may also be present. Ductal carcinoma in situ (DCIS) usually presents with abnormal findings on mammography, but can less frequently present with a lump or nipple discharge in women, whereas in men with DCIS, nipple discharge is the common presentation. Infection in a breast, either mastitis or breast abscess may cause a discharge. Eczema of the nipple may result in a discharge with crusting of the nipple skin. Nipple discharge may be due to breast cancer, particularly if there is an accompanying breast lump. A blood-stained discharge may appear in Paget's disease. Milky Some condition that cause a raised prolactin can result in a milky liquid appearing from nipples. These include endocrine causes such as pituitary and thyroid disease, and some medications. Such medications include: Medication for hypertension: Methyldopa, reserpine, verapamil Gastrointestinal agents: Cimetidine, metoclopramide Hormones: Estrogen, birth control pill Opiates: Codeine, heroin, methadone, morphine Psychotropic drugs: Antipsychotics, monoamine oxidase inhibitors, neuroleptics, selective serotonin reuptake inhibitors, tricyclic antidepressants Some herbs including anise and fennel have also been implicated as causing leaking of fluid from nipples. Diagnosis The evaluation of milky nipple discharge in a non-pregnant, not breast feeding women is different to the assessment of other abnormal nipple discharge. Often, the cause can be ascertained without performing tests. When blood tests are requested, they usually include thyroid tests and prolactin to rule out hypothyroidism and hyperprolactinemia. Other tests that may be considered include mammography, breast ultrasound, CT scan of the head to rule out a pituitary tumour, breast biopsy, x-ray imaging of breast ducts or skin biopsy. The absence of cancerous cells in samples