Needle biopsies can be performed with either a very fine needle or a cutting needle large enough to remove a small nugget of tissue.
Fine-needle aspiration, as noted above, uses a fine-gauge needle and syringe, either to remove fluid from a cyst or clusters of cells from a solid mass. Accurate fine-needle aspiration biopsy of a solid mass takes great skill, gained through experience with hundreds of cases.
Core needle biopsy uses a somewhat larger needle with a special cutting edge. The needle is inserted, under local anesthesia, through a small incision in the skin, and a small core of tissue is removed. This technique may not work well for lumps that are very hard or very small. Core needle biopsy may cause some bruising, but rarely leaves a scar, and the procedure is over in a matter of minutes.
At some institutions with extensive experience, aspiration biopsy is considered as reliable as surgical biopsy, trusted to confirm the malignancy of a clinically suspicious mass or, alternatively, to support a benign diagnosis for a breast lump that appears noncancerous. Should the needle biopsy results be uncertain, the diagnosis is pursued with a surgical biopsy. At some institutions, doctors prefer to verify all aspiration biopsy results with a surgical biopsy before proceeding with treatment.
Localization biopsy (also known as needle localization) is a procedure that uses mammography to locate and biopsy breast abnormalities that can be seen on a mammogram but cannot be felt (nonpalpable abnormalities). Localization can be used in conjunction with surgical biopsy, fine needle aspiration, or core needle biopsy.
For a surgical biopsy, the radiologist relocates the abnormality on a mammogram (or a sonogram) just prior to surgery. Using the mammogram as a guide, the radiologist inserts a fine needle or wire so the tip rests in the suspect area-typically, an area of microcalcifications. (The breast may look bizarre with a needle sticking out of it, but the procedure is remarkably pain free.) The needle is anchored with a gauze bandage, and a second mammogram is taken to confirm that the needle is on target.
The woman, along with her mammograms, goes to the operating room, where the surgeon locates and cuts out the needle-targeted area. The more precisely the needle is placed, the less tissue needs to be removed.
Sometimes the surgeon will be able to feel the lump during surgery. In other cases, especially where the mammogram showed only microcalcifications, the mass can be neither seen nor felt. To make sure the surgical specimen in fact contains the abnormality, it is x-rayed on the spot. If this specimen x-ray fails to show the mass or the calcifications, the surgeon is able to remove additional tissue.