Cysts may be single or multiple. They are well defined, smooth walled, echo free and demonstrate distal enhancement due to increased through transmission of sound. Sometimes the cyst refills and further cysts may develop in the same or the other breast. They can vary in size from mm to cm. Cysts do not develop into cancers, though single large ones are slightly more common in the breasts of women with cancer.
Fibroadenomas are solid, benign breast lumps.
They are usually round or oval, regular in outline and homogenous in texture. A diagnosis can be made by drawing off some cells with a needle. A cytologist is on hand to look at the cells immediately. They are usually left in situ. Lipomas and sebaceous cysts are other types of benign tumour, fibroadenoma being the most common.