Hard lumps on the left side of the breast are related to breast fibroids, mastopexy, and acute mastitis. Under normal circumstances, the breasts are soft and elastic, and there will be no pain or hard lumps, but a hard lump on the left side of the breast should be alarmed and considered to be related to breast fibroids, because when women’s ovarian function is too vigorous, hormone levels are too high and the internal regulation is imbalanced, the glandular epithelium and fibrous tissue of the breast will overgrow and form breast fibroids. Usually, breast fibroids are not easily detected, but when you touch your breasts during bathing or physical examination, you will find a local painless lump, and due to hormonal imbalance, excessive growth of ducts and lobules of the breast will lead to breast hyperplasia, and the lump will be on the left side of the breast. A local lump with pain is considered to be acute mastitis. In women who are breastfeeding for the first time, the nipple area is delicate and can be damaged when the baby sucks on it, causing mastitis to form when bacteria invade the ducts.