A lump in the breast can be caused by a number of reasons: 1. It may be a lobe of the breast, which may appear as a hard lump when touched, which is normal. 2. A benign tumor in the breast, such as a fibroadenoma of the breast, may appear as a lump, which can be large or small. 3. A lump in the breast may be a cyst in the breast, which is a lump in the breast, but is elastic and not hard when touched, and the lump is fluid inside. The lump in the breast may be a malignant tumor of the breast, such as breast cancer, which manifests itself as a lump in the breast and is not painful, which is a painless lump. 5. The lump in the breast may be an inflammation of the breast, which is red, swollen, hot, painful, feverish and at the same time breastfeeding, the most common lump in the breast is an inflammation of the breast or a breast abscess. The most common cause of breast lumps is inflammation of the breast and breast abscess. The specific cause of the lump should be examined at the hospital, such as ultrasound, mammography or even MRI to confirm the cause of the lump.