Some people need an excisional biopsy instead of a needle biopsy.
With excisional biopsy, the whole abnormal area (plus some of the surrounding normal tissue) is removed.
A surgeon performs the procedure in an operating room. He/she will use local anesthetic to numb the area that will be biopsied and you will also get IV sedation (rather than general anesthesia). You probably won't need to stay overnight in the hospital.
Before surgery, a wire-localization or needle-localization procedure may be done. During this procedure, a radiologist uses a mammogram or ultrasound image to guide a very thin wire into the suspicious area of the breast. The surgeon then uses this wire to find the area during surgery.
The breast tissue that is removed is usually X-rayed. This lets the surgeon and radiologist match the suspicious areas on the mammogram with those in the biopsy tissue. If the areas match, the correct tissue was removed. If the areas do not match, the surgeon may try again to remove the correct tissue or may wait to do another biopsy.
Although the goal of an excisional biopsy is to diagnose cancer, sometimes the surgeon may be able to fully remove the cancer. In these cases, excisional biopsy may be the only breast surgery needed to treat the cancer. For others, lymph nodes may also need to be removed in a second surgery at a later date.
Learn more about breast cancer treatment.
If the biopsy shows cancer, a pathologist will study all the tissue removed during surgery to determine whether there is a wide enough rim of normal tissue surrounding the tumor. This rim (called a margin) helps show whether or not all of the tumor was removed.
Clean (also called "uninvolved", "negative" or "clear") margins mean there is a wide enough rim of normal tissue surrounding the tumor. In most cases, when margins are clean, no further surgery is needed.
Positive (also called “involved”) margins mean there are cancer cells in the tissue surrounding the tumor, and more surgery is needed to get clean margins. More surgery may also be done when the tumor margins are not wide enough.
Preserving the tissue sample for pathology
The tissue sample is sent to a pathologist. The pathologist preserves the sample and then studies it under a microscope. Learn more about pathology exams.
Formalin fixed paraffin embedded tissue
In the U.S., the standard way to preserve a tissue sample is called formalin fixed paraffin embedded tissue. The sample is treated with a substance called formalin, which hardens the tissue and prevents it from breaking down over time. Then, the sample is embedded in a block of paraffin (wax).
In some cases, part of the biopsy sample is frozen in the pathology lab during a surgical biopsy. The pathologist examines thin sections of this frozen sample under a microscope to check for cancer cells or to assess the margins (see how close the cancer cells are to the edges of the sample).
Although a frozen section can give a quick check of the tissue sample, it may be linked to false negative or false positive results . A false negative result suggests cancer is not present when in fact, it is. A false positive result suggests cancer is present when it is not. For this reason, the results from a frozen sample always need to be confirmed by other methods, which can take several days.
Advantages of excisional biopsy
Surgical biopsy is accurate and gives few false negative results.
Excisional biopsy also gives information that helps plan treatment, including:
Learn more about these factors.
In some cases, excisional biopsy is the only surgery needed to remove the tumor.
Drawbacks of excisional biopsy
An excisional biopsy is a surgical procedure, so it is more invasive than a needle biopsy. The recovery time is longer and more uncomfortable. There is also a greater risk of infection and bruising. The amount of tissue removed can also change the look and feel of the breast.
If the biopsy results are benign (not cancer), then more surgery may have been done than was needed.