A breast biopsy is the removal of cells or tissue from a suspicious mass. The tissue or cells are then examined under a microscope to check for breast cancer cells. A biopsy may be performed when an abnormal finding in the breast is discovered during a mammogram, ultrasound, or physical examination. A biopsy is the only way to determine if a potential trouble spot is malignant (cancerous) or benign.
There are many types of breast biopsy procedures. The method recommended by your doctor will depend on how large your breast lump or abnormal area is; where in the breast it is located; how many lumps or abnormal areas such as suspicious calcifications are present; if you have any other medical problems; and what your personal preferences are.
Fine needle aspiration (FNA): Fine needle aspiration is a non-surgical form of breast biopsy in which a small needle is used to withdraw a sample of cells from the breast lump. If the lump is a cyst (fluid-filled sac), removal of the fluid will cause the cyst to collapse. If the lump is solid, cells can be smeared onto slides for examination.
Core biopsy: Similar to FNA, but a core biopsy uses a larger needle because actual breast tissue is removed. A sample of the lump is removed, but not the entire lump. The types of core biopsies include ultrasound-guided core biopsy and stereotactic biopsy.
Ultrasound-guided core biopsy: This technique obtains breast tissue without surgery. A biopsy needle is placed into the breast tissue. Ultrasound helps confirm correct needle placement so the exact location of the abnormality is biopsied. Ultrasound can distinguish many benign lesions, such as fluid-filled cysts, from solid lesions. Tissue samples are then taken through the needle.
Stereotactic biopsy: Stereotactic biopsy involves centering the area to be tested in the window of a specially designed instrument. Mammogram films called SCOUT films are taken so the radiologist can examine the breast tissue. Using a local anesthetic, the radiologist makes a small opening in the skin. A sterile biopsy needle is placed into the breast tissue area to be biopsied. Computerized pictures help confirm the exact needle placement. Tissue samples are taken through the needle. It is common to take multiple tissue samples (about three to five).
Open excisional biopsy: An open excisional biopsy is the surgical removal of the entire lump. The tissue is then studied under a microscope. If a rim of normal breast tissue is taken all the way around a lump (called a lumpectomy), then the biopsy can also serve as part of breast cancer treatment (removal of the cancerous tumor). This is sometimes done with wire localization. In this technique, a wire is inserted through a needle into the area to be biopsied. An X-ray is taken to make sure it is in the right place. A small hook at the end of the wire keeps it in position. The surgeon uses this wire as a guide to locate the abnormal tissue to be removed.
Sentinel node biopsy: A biopsy method known as sentinel node biopsy can be used to pinpoint the first lymph node into which a tumor drains (called the sentinel node). This helps to ensure only the nodes most likely to have cancer are removed. To locate the sentinel node, a radioactive tracer, a blue dye, or both, are injected into the area around the tumor before a mastectomy is performed. The tracer travels the same path to the lymph nodes that the cancer cells would take, making it possible for the surgeon to determine the one or two nodes most likely to test positive for cancer.
Cells or tissues that are removed using any of the methods described above are given to a pathologist, a doctor who specializes in diagnosing abnormal tissue changes.