If you are a candidate for a needle biopsy, you will have a needle biopsy before an excisional biopsy. In some cases, such as when the abnormal area is deep and close to the chest wall, an excisional biopsy will be done first.
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 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 find the cancer and fully remove it. In some cases, excisional biopsy may be the only surgery needed. For others, lymph nodes may also need to be removed.
Learn more about breast cancer treatment.
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 United States, 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.
Although a frozen section can give a quick check of the tissue sample, it may be linked to false negative results . A false negative result shows cancer is not present when in fact, it is. For this reason, the results always need to be confirmed by other methods, which can take several days.
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 margin of normal tissue helps show whether all of the abnormal tissue was removed.
Clean (also called "uninvolved", "negative" or "clear") margins mean there is a wide enough of a rim of normal tissue surrounding the tumor that was removed. In most cases, when margins are clean, no further surgery is needed.
If cancer cells extend to the edge of the sample or the margins, they are considered positive (also called "involved") and more surgery is needed to get clean margins. More surgery may also be done in some cases where there is not a wide enough rim of normal tissue surrounding the tumor.
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.
Excisional biopsy also may be the only surgery needed to remove the tumor.
Drawbacks of excisional biopsy
An excisional biopsy is more invasive than a needle biopsy. The recovery time is longer and more uncomfortable and there is 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.