Ductal carcinoma in situ, also known as intraductal carcinoma of the breast, is an early stage malignant tumor of the breast, when the tumor does not break through the ductal basement membrane, so it is called carcinoma in situ. According to the pathological biopsy of the tumor, the characteristics of the tumor cells can be judged, and ductal carcinoma in situ may also be special types such as sweat gland carcinoma in situ (Paget’s disease), clear cell carcinoma, squamous cell ductal carcinoma in situ and so on. Most of the people with this disease do not have obvious clinical symptoms, but some of them may have nipple discharge, breast lumps, uneven breast texture, etc. Nipple discharge is usually yellow, transparent and clear, and with the progression of the disease, it may have blood in the discharge. It is recommended that the relevant groups of people to timely consult the doctor for regular treatment, to avoid the progression of the disease, resulting in serious consequences.