High-grade ductal carcinoma in situ usually refers to a type of ductal carcinoma in situ with poorer differentiation and higher malignancy, which has a better overall prognosis, but a slightly higher risk of recurrence after resection compared to low-grade ductal carcinoma in situ. Ductal carcinoma in situ refers to cancer cells that have already appeared but are at a very early stage, where the cancer cells are gathered within the ductal area and have not yet broken through the basement membrane to grow into the surrounding tissues. Ductal carcinoma in situ is a very early stage tumor that theoretically will not spread to other places and can be cured with complete surgery, but it does not mean that it will not recur. Under the microscope, the cut tumor cells will also be observed clinically. If the ductal carcinoma in situ has more nuclear schizophrenia and higher mitotic rate, it is judged according to certain grade, and it is usually judged as high-grade ductal carcinoma in situ, which indicates that although the cancer cells are very early, the malignancy is higher, and the risk of recurrence is slightly higher later, which is a pathological concept.