Types of Breast Biopsy
The diagnosis of breast cancer is always made by removing all or part of the abnormal area and looking at it under a microscope. This is called a biopsy. There are five different types of biopsies:
-If we remove all of the lump, it is called an excisional biopsy. Usually this is what we mean when we talk about a "breast biopsy".
-If we remove part of the lump, it is called an incisional biopsy.
-If we use a needle to obtain a few cells from within the lump it is called a needle aspiration biopsy.
-If we use a large needle to remove a small cylinder of tissue from within the lump it is called a core needle biopsy.
-If the core needle biopsy is done using x-ray to guide the needle into the lump it is called a stereotactically guided core needle biopsy or a Mammotome biopsy.
Incisional or excisional biopsies are procedures usually done in a surgery center or hospital operating room. Usually the entire lump is removed and sent to the pathologist. He is the physician who will look at the lump under a microscope and give us a diagnosis. The day that we do the biopsy he may freeze a small piece, take a thin slice, and look at it right away. This is called a frozen section. The frozen section can usually give us an answer, but not always. We rely on the permanent section report for the final determination. The permanent sections are made by soaking the specimen in paraffin (wax) overnight. This allows very precise, thin slices to be made. When these are viewed under the microscope the clarity is greater than that of the frozen section. Also, the pathologist has the time to look at many different areas of the lump when he makes the permanent sections, so he can give us more information about the relationship of the lump to the surrounding breast tissue.
A needle aspiration biopsy can be done in the office. A needle is inserted into a lump and a few cells are withdrawn into the needle. The cells are placed on a glass microscope slide, sent to the lab, stained, and looked at under the microscope, very much like a Pap smear. Sometimes this will tell us if the lump is a cancer. However, this test has its limitations, and we usually do not rely completely on this for diagnosis. If this test comes back normal we still recommend that the entire lump be removed. If the needle biopsy comes back showing cancer we confirm this by removing the entire lump and looking at it under the microscope. Since we remove the lump whether the needle biopsy is positive or negative, the usefulness of this test is limited, and this is only done in certain situations.
The main difference between a needle aspiration biopsy and an excisional biopsy is that with a needle biopsy, the pathologist is looking at individual cells and trying to determine if they have characteristics that make them look like cancer cells. This is called a cytologic examination. When an excisional biopsy is performed, the pathologist looks at both the characteristics of the cells and how they are interacting with the neighboring cells. This is called a histologic section and is more accurate than a needle biopsy.
With a Stereotactically guided core needle biopsy a mammogram is done, and the abnormality is viewed by the radiologist on a monitor. The radiologist uses injections of local anesthesia to numb the area, and uses a special needle to perform the biopsy. The entire lump is not usually removed, but several small cylinders of tissue about 1/16" in diameter are removed. This is very accurate in determining the nature of a breast abnormality. However, the lump may remain noticeable to touch and visible on mammogram even after the biopsy.
-If the steriotactic biopsy shows a benign abnormality, nothing further needs to be done.
-If it is inconclusive or more information about the abnormality is needed, an excisional biopsy will need to be done, usually with localization technique.
-If it shows cancer, additional surgical treatment will be necessary.