Breast cyst

Breast cyst
Ultrasound scan showing a small cyst in the breast
Specialty	General surgery

A breast cyst is a cyst, a fluid-filled sac, within the breast. One breast can have one or more cysts. They are often described as round or oval lumps with distinct edges. In texture, a breast cyst usually feels like a soft grape or a water-filled balloon, but sometimes a breast cyst feels firm.^[1]

Breast cysts can be painful and may be worrisome but are generally benign. They are most common in pre-menopausal women in their 30s or 40s. They usually disappear after menopause, but may persist or reappear when using hormone therapy.^[1] They are also common in adolescents.^[2] Breast cysts can be part of fibrocystic disease. The pain and swelling is usually worse in the second half of the menstrual cycle or during pregnancy.

Treating breast cysts is usually not necessary unless they are painful or cause discomfort. In most cases, the discomfort they cause may be alleviated by draining the fluid from the cyst. The cysts form as a result of the growth of the milk glands.^[3] While some large cysts feel like lumps, most cysts cannot be identified during physical examinations.

Breast cysts are not to be confused with "milk cysts" (galactoceles), which usually appear during weaning.