Round hard lumps in the middle of the breast are associated with breast fibroids, breast cysts or normal breast tissue. When young women have round hard lumps in their breasts, they are considered to be caused by breast fibroids. The body’s endocrine disorder and excessive secretion of estrogen make the lobular fibroblasts of the breast more sensitive to estrogen, and hormonal overstimulation leads to abnormal proliferation of lobular fibroblasts, which produces round hard lumps in the breast. Genetic, viral infection, endocrine disorders can lead to breast cysts. Local bacterial infection can lead to round lumps in the breast area, which can cause local pain when pressed, and can also be considered normal breast tissue.