Benign and Malignant Breast Cysts

Breast cysts are fluid-filled sacs within the breasts. They may be malignant (cancerous ) or benign (noncancerous); may occur alone or in clusters in one or both breasts; and may be tiny and unnoticeable, or large and painful to the touch. Benign cysts occur in the breast's glands and, occasionally, connective tissue, whereas cancerous cysts form in the ducts or lobules. Benign breast cysts are quite common, occurring in about half of all women, most commonly when they are perimenopausal (between the ages of 40 and 50). Breast cysts can cause uncomfortable symptoms, and sometimes indicate the development of cancer.

If a breast cyst appears suspicious, an examination and one or more imaging tests will be performed to determine whether it is benign or malignant. Some benign cysts shrink or stop growing on their own. For those that do not, treatment is typically drainage via fine-needle aspiration (FNA) in an attempt to relieve painful symptoms. Recurring cysts may need to be removed surgically.

Characteristics of a malignant cyst include:

  • Irregular shape
  • Firm consistency
  • "Sharp" edges
  • Blood-filled fluid

A malignant cyst, along with some of the surrounding tissue, is surgically excised.

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