Womens Health

Breast Cyst Found on a Mammogram

Frederick R. Jelovsek MD

I just had a mammo, and had to go back for another one and an ultrasound, they found a 1/2 inch cyst with a smaller one next to it. My Gyno is leaving it up to me to see a surgeon, What are your thoughts on this?"

"I am 42 white female, I also have cysts on my ovaries, fibroid on my uterus and just had the Leep procedure done to get rid of bad cells on my cervix. My periods are regular, but I do clot a lot and bleed heavily."

Cathy

My thoughts are that you should go ahead and have the cyst aspirated. I hope the following comments will shed light on that simple statement.

Mammograms do not detect breast cysts. They just show dense masses. If the radiologist suspects the mass may have fluid in it, then an ultrasound is performed. If there is fluid in the mass, a needle aspiration of the cyst may be suggested. The rule-of-thumb is that any breast mass needs to be evaluated as a possible malignancy. If the mass is known to be solid, it is surgically excised and sent to pathologic analysis to see if it is a cancer. If it is a cyst, the fluid can be drawn off and, if not bloody, it is a benign cyst and continued observation is the course of action.

Mammograms may also look for calcifications which can be a sign of a benign or malignant microscopic mass that would need to be evaluated. Ultrasound can also pick up micro calcifications in the breast and is actually better at identifying calcifications in invasive and in-situ breast cancer than it is in identifying them in benign fibrocystic conditions (1.

The basic principle is that any discrete, solid breast mass needs to be biopsied and any suspicious mass effect on mammogram or ultrasound needs to be confirmed as benign. In the case of a cyst, this means aspiration of the cystic fluid. In the case of a suspicious finding on imaging that does not have fluid in it, a core needle aspiration biopsy (withdrawing tissue cells into the needle and syringe rather than fluid) is used to confirm benign changes.

How common are cysts in the breast?

Breast cysts may occur in up to 20-50% of reproductive age women at sometime in their life. Most cysts are very small but large cysts, macrocysts occur in up to 7% of women (2). The peak incidence is in premenopausal women aged 40-50. Less than 5% of cysts are in women over 60 (3).

The glands and ducts of the breasts secrete fluid all of the time even though they are not lactating. The amount is so small it is not noticeable on a daily basis but if a duct plugs up with normally sloughed skin cells, the fluid builds up and a cyst is formed. Cysts may be single or multiple. They are not seen as cysts on mammography, just as a dense mass or masses. If the radiologist suspects the mass is a cyst, an ultrasound is performed to see if there is fluid inside the mass. If there is, this is called a breast cyst.

The next step is to determine if the breast cyst has more benign characteristics or could it possibly be malignant. Benign cysts are round or oval, well-circumscribed and usually greater than 1.4 cm in size; malignant characteristics include irregular shape, micronodular groups of fluid collection and having sharp edges (4).

Are cysts in the breast the same as fibrocystic breasts?

No. Fibrocystic changes are mostly thickened areas of the breast glands and supporting fibrous tissue. The breast normally is composed of mostly fatty tissue. The glands and ducts are only a small part of the breast unless they undergo fibrocystic change or are stimulated by pregnancy. Fibrocystic change is much more a fibrous than cystic but some cysts can occur.

Cysts can occur on their own or in a setting of fibrocystic change and when they do, they present more as a discrete mass you can get your fingers around. Fibrocystic change alone is a diffuse, rubbery thickening without any areas containing much fluid.

How are the breast cysts treated - what does a surgeon do?

If there is a cystic, fluid filled area seen on ultrasound of the breast and the characteristics are benign, the usual treatment is to put a needle in the cyst and draw off (aspirate) the fluid. If the fluid is clear or yellow color but with no evidence of blood in it, the fluid is just discarded since this always means the cyst is non cancerous (5). The woman just then waits to see if the cyst recurs. If it does not, no other treatment is needed. If it does recur, an excision of the cyst or a 2nd aspiration may be performed.

If on ultrasound the cyst appears to have any characteristics of malignancy, or if on aspiration of a benign cyst bloody fluid is found, then the cyst is surgically excised just as if it were a solid lesion.

Will cysts

 in the breast keep coming back?

They may. In women who have breast cyst aspiration, about 40% will have recurrences with two to five recurrences in 36 per cent and more than five recurrences in 4 per cent (6). It seems that the younger the age at which a woman has breast cysts, the more likely it is she will have a recurrence.

What causes cysts in the breast?

No one knows, other than the ducts get plugged up. It is probably not due to hormones. Birth control pills do not cause breast cysts and actually the newer low dose pills seem to lower the incidence of fibrocystic breast disease (7). After menopause, hormone replacement does not cause cyst development (8). The different progestins can increase breast density more so than the estrogen component but neither seem to produce cysts.

 

Other Related Articles

Breast Nipple Discharge and Its Evaluation
Fibrocystic Breast Disease and the Perimenopause
Risk for Breast Cancer in Younger Women

 

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