Mammary cysts are found in women of all ages. Active secretion of fluid occurs in the breast duct and lobular system (milk forming structures) even when lactation is not occurring. Cysts may form as a result of duct obstruction, usually by a keratin plug, or as a result of the involutional or aging process. Cysts may be solitary or multiple and 20 to 50 percent of women have breast cysts.
Cysts usually appear as rounded densities on a mammogram. Cysts cannot be accurately diagnosed by mammography, as they cannot be distinguished from other well defined masses. When a new or larger well defined mass is seen mammographically, an ultrasound study is usually recommended to establish whether a mass is cystic or solid in nature.
Cysts may be under tension from undrained secretions. Cyst aspiration using ultrasound guidance is commonly employed to relieve associated discomfort. Cysts also may contain blood or debris, producing an indeterminate appearance at ultrasound; cyst aspiration is most commonly performed at our institution to differentiate a cyst containing blood ro debris from a solid mass. Occasionally we perform cyst aspirations on women with multiple large cysts prior to mammography so that the underlying glandular tissues are better seen.
The risks of cyst aspiration are resultant pain (usually mild, if any), bleeding resulting in a small or large bruise, and infection (very rare). The benefit of differentiating a cyst from the rare well-marginated malignancy outweighs these risks.
I usually use ultrasound guidance for cyst aspirations. I do not generally use local anesthesia because administering the anesthetic is frequently more painful to the patient than aspirating without it. However, I will administer lidocaine or xylocaine at the patient’s request. We clean the area of the breast to be aspirated with alcohol and use alcohol as our transducer medium instead of gel. I frequently use a 20 gauge needle (comparable to a needle used to draw blood) for breast cyst aspiration. The procedure may take several seconds to several minutes to complete.
Cyst fluid is almost never colorless, but is often white, yellow, green, brown, or frankly bloody. I usually only submit the aspirated fluid for pathologic evaluation if it is bloody or if there is a residual breast mass after aspiration. Even in these circumstances, the underlying pathology is almost always benign. If I do submit the fluid for evaluation, results are generally available the afternoon of the next business day.
Cyst aspiration is generally not a traumatic or painful procedure for patients, can be very helpful diagnostically, and can sometimes relieve breast pain and discomfort. If you have any questions about this procedure please e-mail me at [email protected].
Authored by: Christin Dickerson, M.D.
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