What is FNA?

Fine needle aspiration (FNA) is a percutaneous ("through the skin") procedure that uses a fine gauge needle (22 or 25 gauge) and a syringe to sample fluid from a breast cyst or remove clusters of cells from a solid mass. With FNA, the cellular material taken from the breast is usually sent to the pathology laboratory for analysis. The needle used during FNA is smaller than a needle that is normally used to draw blood. If the radiologist or surgeon just drains fluid from a cyst and does not send the sample to the pathology laboratory for analysis, the procedure is simply called cyst aspiration.

How is FNA Performed?

First, the skin of the breast is cleaned. If a breast lump can be felt, the radiologist or surgeon will guide a needle into the area of concern by palpating (feeling) the lump. If the lump is non-palpable (cannot be felt), the FNA procedure will be done under image-guidance using either stereotactic mammography or ultrasound with the patient in either the upright or prone (face down) position. Stereotactic mammography involves using computers to pinpoint the exact location of a breast mass based on mammograms (x-rays) taken from two different angles. The computer coordinates will help the physician to guide the needle to the correct area in the breast. With ultrasound, the radiologist or surgeon will watch the needle on the ultrasound monitor to help guide it to the area of concern. FNA is usually performed under ultrasound image guidance.

After the needle is placed into the breast in the region of the lesion (abnormality), a vacuum is created and multiple in and out needle motions are performed. Several needle insertions are usually required to ensure that an adequate tissue sample is taken. The samples are then smeared on a microscope slide and are: 1) allowed to dry in air, 2) are "fixed" by spraying, or 3) are immersed in a liquid. The fixed smears are then stained and examined by a pathologist under the microscope.

FNA does not require stitches and can usually be performed on an outpatient basis. A very small bandage is placed over the area after the procedure. Many patients resume their normal lifestyle and routine the same day of the FNA procedure.

Note: The effectiveness of FNA is largely operator-dependent; it requires a skilled radiologist or surgeon who has gained experience by performing several cases.

How Do FNA Samples Appear?

Fluid extracted from the breast lump may be clear, straw-colored, green or brown tinged, white, yellow, or more rarely, bloody. In most cases, these fluids are benign (non-cancerous). If the fluid is not bloody, it is usually simply discarded because there is not typically any benefit gained from microscopic examination by a pathologist. However, bloody fluid may indicate cancer and is usually sent to the laboratory for analysis.

How Should Patients Prepare for FNA?

Prior to FNA, the skin of the breast is cleansed and then may be anesthetized with a small hypodermic needle. Many times, the breast is not anesthetized for FNA because administering the anesthesia tends to cause more pain for the patient than the procedure itself. Also, lidocaine (an anesthesia) may cause artifacts to appear in the cytology sample when examined under the microscope.

Patients may eat a light meal prior to the procedure. A comfortable two piece garment should be worn. Women should not wear talcum powder, deodorant, lotion, or perfume under their arms or on their breasts on the day of the procedure (since these may cause image artifacts or other problems). Patients who take blood thinners or aspirin should talk to their physicians about whether they should discontinue using them prior to FNA. Any jewelry worn (especially earrings or necklaces) should be easily and quickly removable.

What are the Advantages and Disadvantages to FNA?

FNA is the fastest and easiest method of breast biopsy, and the results are rapidly available. FNA is excellent for confirming breast cysts, and since the procedure does not require stitches, patients are usually able to resume normal activity almost immediately after the procedure.

One disadvantage of FNA is that the procedure only removes very small samples of tissue or cells from the breast. If the sample is benign fluid (for example, a cyst), then the procedure is ideal. However, if the tissue is solid or if a sample of cloudy, suspicious-looking fluid is obtained, the small number of cells removed by FNA only allow for a cytologic (cell) diagnosis. This can be an incomplete assessment because the cells cannot be evaluated in relation to the surrounding tissue.

For example, a pathologist may diagnose ductal carcinoma in situ (DCIS), a non-invasive breast cancer, based on the FNA breast sample obtained when in fact, the patient has infiltrating ductal carcinoma (IDC), in a nearby area. IDC is an invasive and potentially more serious breast cancer. A larger sample (such as that obtained with core needle or vacuum-assisted biopsy) can help the pathologist determine the extent of the cancer.  

Updated: August 29, 2007

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