A thick tendon in the breast is associated with breast hyperplasia, breast duct lesions, and breast fibroids. Mammary gland hyperplasia is more common clinically. Hormonal changes in the body during the premenstrual period, emotional fluctuations and other factors can lead to excessive hyperplasia in the breast area, and touching the breast with your hand will reveal a strip of tendons in the upper part of the outer breast and the armpit near the breast, which feels like a rubber band and causes local pain when touching, dressing or exercising. When the breast ducts are inflamed, they will gradually become thicker, harder, and more painful, and will feel thicker when touched. Breast fibroids are benign tumors that grow slowly, but the increased secretion of estrogen and progesterone during pregnancy and lactation will stimulate the growth of fibroids, which can be touched by hand and can be considered for surgical removal if necessary.