Cysts are fluid-filled bubbles, similar to blisters, in the breast tissue. Most cysts develop rapidly and then stay the same size. A small number shrink or continue to grow. Cysts are often too small to feel. However, on ultrasound they appear as a round clear shape with a distinct outline. Larger cysts can be felt in the breast tissue.
Breast cysts - Diagnosis and treatment - Mayo Clinic
These changes are sometimes called fibrocystic changes , and used to be called fibrocystic disease. Areas of fibrosis feel rubbery, firm, or hard to the touch. They are often felt as a round, movable lump, which might also be tender to the touch. Cysts begin when fluid starts to build up inside the breast glands. These can be felt easily and can be as large as 1 or 2 inches across. Simple cysts are not usually a cause for concern. Neither fibrosis nor simple cysts increase your risk of later developing breast cancer.
Cystic Breast Masses and the ACRIN 6666 Experience
Breast cysts are round or oval structures filled with fluid. Most breast cysts are benign and do not increase your risk of breast cancer. They can be very tiny, or they can be large enough to feel through the skin or see on an imaging test a grossly evident cyst, or gross cyst. Many cysts fall somewhere in between. In more than half of cases, women develop multiple cysts, either all at once or over a period of time.
There are different types of breast lumps. The following descriptions and illustraitons provides some details. If you have any questions, follow-up with your doctor. Not all tumors are malignant cancerous.