Breasts grow a soybean-sized swelling, painless and itchy may be caused by skin abnormalities, may also be caused by breast fibroids, lipomas and other diseases. 1, skin superfluous organisms: when the patient’s breast skin has been traumatized, or local wounds appear bacterial infection and other factors, can lead to the formation of skin manifestations superfluous organisms. Skin growths usually have no obvious pain and discomfort, varying in size and diameter, and can develop into the same size as soybean. 2, breast fibroids: breast fibroids are common benign breast diseases, mainly due to breast fibroblasts are more sensitive to estrogen. Most of the patients can manifest as painless lumps, may appear different degrees of swelling and pain during menstruation, and generally will not have malignant changes. 3、Lipoma: Lipoma is a relatively common benign soft tissue tumor, mostly occurring in the back and waist, but also in the female side of the breast and other parts. Superficial lipomas are single in number or present multiple subcutaneous lumps, which will not be accompanied by obvious pain. There are many reasons why a soybean-sized lump grows on the breast without pain or itching, and it is recommended that you seek medical attention in time to avoid further aggravation of the condition.