Fibrocystic changes are a set of breast symptoms that include pain, cysts, and general lumpiness in your breasts. The word fibrocystic comes from the terms fibrous tissue and cyst. Fibrous tissue is tough, strong tissue that feels like it's made of a lot of fibers. A cyst is a small, fluid-filled sac that grows inside your body. Fibrocystic changes in the breast is not a single disease.