Breast hypoechoic mass without blood flow signal may be caused by mastitis, breast cystic hyperplasia, breast fibroadenoma and other diseases. 1. Mastitis: Mastitis is mainly related to autoimmune factors, breast trauma, drug stimulation, bacterial infection, etc. There are redness, swelling, heat and pain, and the lumps can be seen as hypoechoic lumps without blood flow signals under laboratory examination. 2. Breast cystic hyperplasia: Breast hypoechoic light mass without blood flow signal may be caused by breast lumps produced by breast cystic hyperplasia, accompanied by breast pain and occasional nipple discharge, which is related to the stimulation of ovarian endocrine. 3. Mammary fibroadenoma: Mammary fibroadenoma is a common benign breast disease, mainly due to the abnormal increase in the sensitivity of breast tissue to estrogen caused by the breast often appear round, smooth, clear boundaries, good mobility of the painless mass, the examination found in the breast hypoechoic light mass, did not see blood flow signal. There are many reasons for breast hypoechoic light mass without blood flow signal, and there may be other reasons such as malignant tumors, etc. It is recommended that the patient consult a doctor in time to clarify the cause of the disease.