Adenofibroma, also known as fibroadenoma, is the most common of all benign tumors of the breast. The incidence of adenofibroma in the general population has not been accurately reported. What are the causes of breast fibroids? What are the characteristics? What are the clinical manifestations? How is it treated once detected? Many women do not have a proper understanding of breast fibroids, so we will share the following knowledge with you: The age of onset of breast fibroids is 9 to 68 years old, mostly young women around 20 years old. 60% of patients are less than 30 years old. The cause of mammary fibroids is unknown. Since the disease rarely occurs before menarche or after menopause; estrogen can accelerate the growth of adenofibroma in pregnant women and also induce the occurrence of adenofibroma in animals; significantly higher levels of estrone and estradiol in adenofibroma suggest that high estrogen levels or local weaving of the breast that is too sensitive to the action of estrogen may be closely related to the occurrence of adenofibroma. Very few adenofibromas in the breast can become malignant, with the fibrous component becoming sarcoma and the glandular epithelial component becoming carcinoma. It is important to note that breast fibroids grow rapidly during pregnancy and lactation, and are difficult to distinguish from breast cancer during pregnancy, so ultrasound examination of the breast is recommended before pregnancy. Clinical manifestations of breast fibroids Breast fibroids are commonly found in young women. Breast lumps are found unintentionally, mostly without pain, pressure and abnormal nipple secretion. The lump is mostly round, oval or flat. They have clear borders, smooth surface, firm texture, and high mobility, and are not adherent to the epidermis or pectoral muscle. They can be located in all parts of the breast, mostly in the upper quadrant. Most of them are solitary, but about 10%-25% are multiple in one or both mammary glands. It can be multiple at the same time or multiple at different times. The growth rate of tumor is very slow, with no change for several years or more than 10 years. The menstrual cycle has no effect on the growth of tumor, some of them have slight swelling and pain during menstruation, and slightly increase during pregnancy and lactation. Some of them have slight swelling and pain during menstruation, and slightly increase during pregnancy and lactation. A few of them increase rapidly and are called giant fibroadenoma. The axillary lymph nodes are usually not enlarged. If the tumor suddenly increases rapidly after many years of quiescence, with pain and enlarged axillary lymph nodes, malignant transformation should be highly suspected. Individual adenofibromas that occur before menarche can rapidly increase in size a few months or a year or two after menarche, mostly >5cm, up to 20cm, and occupy the whole breast, with tense and shiny breast skin, redness and enlarged varicose veins, resembling malignant tumors. However, it does not adhere to the epidermis and can be pushed without pain, and the axillary lymph nodes are not enlarged. It is not difficult to diagnose adenofibroma with the above typical symptoms and signs. If there is some difficulty in diagnosis, mammography, ultrasound, infrared fluoroscopy, fine needle aspiration cytology, etc. can be helpful.