A biopsy is done if the results of either a physical examination or imaging tests, such as a mammogram or ultrasound, show a concerning change in the breast. During a breast biopsy, a sample of tissue is taken from the breast. A pathologist — a doctor who is trained to diagnose disease — then examines the cells or tissue under a microscope to determine whether or not they are cancerous.

There are different types of biopsy methods. These include:

Fine Needle Aspiration

During this procedure, the doctor inserts a very thin needle into the suspicious area of the breast. Cells or fluid are withdrawn (aspirated) from the lump and placed on a slide for examination under a microscope by a pathologist. This type of biopsy is relatively quick, and any discomfort lasts only a few seconds.

Core Needle Biopsy

A core needle biopsy may be used if the pathologist needs a larger tissue sample than what can be obtained with a fine needle aspiration. It can also be used if the tissue removed during a fine needle aspiration did not yield a definitive diagnosis. A core needle biopsy requires a local anesthetic. The doctor inserts a larger, hollow needle into the breast. A thin cylinder of tissue about one inch long is removed and sent to a pathologist for analysis.

Image-Guided Biopsy

If the suspicious area cannot be felt, then a radiologist can use imaging techniques to biopsy the area. These techniques include ultrasound, stereotactic mammographic imaging, and MRI. Which one is used depends on what the abnormality looks like and which technique is most appropriate for visualizing it.

Surgical Biopsy

A surgical biopsy may be done if other biopsy procedures do not provide a definitive diagnosis. A surgical biopsy is also performed if the suspicious area is too deep or too shallow for a core needle biopsy.

If the surgeon cannot feel the area in question, then the radiologist will insert a thin wire or a small radioactive marker known as a seed into the breast. This is done using mammography, ultrasound, or MRI and is called a needle or seed localization. It helps the surgeon pinpoint the right area to biopsy.

A surgical biopsy takes place in an operating room, but it does not usually require an overnight stay in the hospital. During a surgical biopsy, the patient undergoes “twilight” sedation but does not require general anesthesia. A small incision is made on the breast, then the suspicious breast tissue is removed entirely, or a representative sample is removed for analysis.