Dilatation of the milk ducts is a symptom that develops when the diameter of the milk ducts significantly exceeds the normal range and may be the result of ductal hyperplasia and plasma cell mastitis. 1. Breast Duct Hyperplasia: It is the hypertrophy and dilatation of the components of the breast ducts. The ducts of the breast are enlarged near the nipple with small dilatations, and when the dilatation is more pronounced, it is Breast Duct Hyperplasia. It may be related to the menstrual cycle, with the enlargement being more pronounced before menstruation and gradually decreasing after menstruation. 2. Plasma cell mastitis: a chronic non-bacterial inflammation of the mammary gland, due to a variety of problems caused by the mammary duct lumen secretion poor drainage, mammary duct blockage caused by expansion, repeated aseptic inflammation around the ducts, and even fistula, fistula prolonged, etc., and may be associated with autoimmune and local developmental abnormalities. Dilatation of the milk ducts may also be caused by breast tumors, etc. If there is dilatation of the milk ducts, it is necessary to go to the hospital in time, to clarify the cause of the disease, and to actively treat it under the guidance of the doctor.