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can a benign breast cyst turn into cancer

Can a Benign Breast Cyst Turn into Cancer?

According to, about 25% of breast masses turn out to be cysts. Cysts are round or oval organic structures filled with fluid. Many people think we can feel all breast cysts through the skin. Although this is true of many cysts, some are so small they are only detected with diagnostic imaging. A cyst that you can feel OR seen through imaging is a “gross cyst.” Still, some cysts are so tiny that they are virtually undetectable until they grow.

Cysts may also cause pain or tenderness in the breast. Those symptoms usually increase and decrease at different points in the menstrual cycle. More than half of women who have breast cysts develop more than one cyst at the same time.

It is most common for breast cysts to develop in women in their 40s. But, they can occur at any age. Can a benign breast cyst turn into cancer?

Benign versus Malignant Cysts

A benign cyst is a harmless one. It is a mass of tissue and fluid. A malignant cyst, in contrast, is one that is cancerous.

Before Dr. Miltenburg at Breast Institute Houston can diagnose whether a breast cyst is benign or malignant, she will want to categorize it as “simple,” “complex,” or “complicated.”

Simple Cysts

Simple cysts have thin walls which don’t get thicker or thinner in parts. They are completely filled with fluid — they are in no part solid. Simple cysts are always benign.

Complex Cysts

“Complex cysts have irregular or scalloped borders, thick walls, and some evidence of solid areas and/or debris in the fluid.” [] If your doctor suspects the cyst is cancerous, she will drain it with a fine needle. She is looking for blood or other unusual cells, and test them to rule out cancer.

The doctors at Breast Institute Houston want to rule out any chance of cancer. They may also test the solid parts of complex cysts by sending them for a biopsy.

Complicated Cysts

Complicated cysts are “in-between” simple and complex cysts. They may be like simple cysts but show some evidence of debris which should be tested for cancer.

The Difference Between a Tumor and a Cyst

According to, “A tumor is any abnormal mass of tissue or swelling. Like a cyst, a tumor can form in any part of the body. A tumor can be benign or cancerous (malignant).”

So, contrary to popular belief, not all tumors are cancerous. Your doctor must test them with imaging and biopsy to determine whether they are cancerous.

Breast Cancer Screening

Even women with simple cysts (which are always benign) go back for routine breast cancer screening. If you have a complex or complicated cyst (which may be malignant,) your doctor will ask to see you every 6-12 months for 1-2 years to have it retested for cancer growth. If at any point the cyst looks suspicious, your doctor will order a biopsy. Tumors are screened, tested, and managed in much the same way.


Biopsies test the solid parts of breast cysts or tumors to see if they are benign or malignant. Your doctor removes solid tissue cells with a core needle and then examines them under a microscope. On a rare occasion, she may need to remove the cyst or tumor. This is called “excisional biopsy.”

Seeing a Breast Specialist

If you find out you have many cysts or develop new cysts frequently, you should seek management by a breast specialist. This is especially true if you also have other risk factors. One major risk factor is a family history of breast cancer.

The Bottom Line

Don’t jump to conclusions when your doctor says you have a complex or complicated cyst (or tumor.) Most test as benign in the end.

Remember that having benign cysts does not increase breast cancer risk.

Breast Institute Houston

Darlene Miltenberg is a breast care specialist and top breast cancer surgeon in Houston. Get the best care Houston has to offer with Dr. Miltenberg at Breast Institute Houston. Call 713-795-0161 or submit a message to Dr. Miltenberg today.

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Houston Breast Cancer Surgeon

Darlene M. Miltenburg MD, FRCS(C), FACS
Call US 713-795-0161
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