Ductal dilatation of the breast is not always caused by cancer, but is commonly associated with mammary hyperplasia. Due to the uncoordinated and irregular proliferation of breast glands, localized masses may form, as well as localized ductal dilatation, or even cystic lesions, which mainly manifest as hypodense lesions with intact envelope, and patients may also experience painful symptoms. For patients with multiple cysts, they may also show bilateral breast asymmetry. For patients with malignant tumors of the breast, if the ducts are involved, they may also show dilation of the milk ducts, usually with bloody nipple overflow and abnormal changes of the breast skin. Because malignant tumors, also known as breast cancer, are usually infiltrative in nature, they may also show orange peel-like changes due to the involvement of subcutaneous lymphatic vessels in the breast. After the diagnosis of malignant tumor of the breast, radical excision surgery should be actively chosen, and many patients even need radiotherapy or chemotherapy.