Fine needle aspiration (FNA) of the breast is performed by inserting a small-gauge needle attached to a syringe into a cystic breast lesion and extracting any fluid within the cyst. (Dawson) Used most commonly in young women with palpable breast lesions likely to be benign cysts, FNA can serve both diagnostic and therapeutic purposes. (Bell) If the FNA yields clear fluid, and the lesion becomes nonpalpable, you may safely conclude that the lesion was a benign cyst and instruct your patient to return as needed should the cyst recur. If the extracted fluid is not clear, or the lesion remains palpable after the procedure, biopsy is indicated. This section addresses the first situation.

1. Getting ready
2. How to do it
3. Follow up

As with any minimally invasive biopsy technique, the potential exists for false-negative results when the needle fails to sample the lesion (Kreuzer, O'Malley). False-negative results can be minimized by using an imaging modality for guidance in placing the needle. Failure to aspirate an adequate sample may also lead to inadequate or misleading results. For these reasons, FNA for cytology or histology examination is usually done by specialists who have considerable experience with FNA techniques (Cohen). FNA for drainage of a simple cyst, however, is a straight forward procedure that does not require special equipment or advanced training.

Getting ready
Assemble the following equipment:

• nonsterile gloves
• alcohol swabs
• sterile gauze pads
• clear hub needle—size and length of the needle are determined by the size of the lesion and its estimated depth. Recommended needle sizes include:
  • 1-inch 22-gauge
  • 1.5-inch 22-gauge
  • 1-inch 23 gauge or 25 gauge
• A disposable 10-mL syringe with a Luer-Lok tip
• Ethyl chloride spray (or an ice cube) for topical anesthesia

Review any mammograms or other radiologic studies available. Discuss the risks of the procedure (minor discomfort, bleeding, infection) with the patient and obtain informed consent.

How to do it
Put on the gloves and prepare the needle and syringe. Localize the lesion between the thumb and second finger of your non-dominant hand. Clean the site with an alcohol swab, then either dry it with gauze or allow the alcohol to evaporate. To achieve local anesthesia, spray the site with ethyl chloride until the skin changes color slightly. You must now work quickly since the anesthetic effect is short-lived.

Continuing to use your non-dominant hand to stabilize the tissue, take the needle and syringe in your dominant hand and aim them toward the identified tissue. Advance the needle in a direction perpendicular to the patient's skin. As soon as you feel the needle entering the patient's skin, begin to pull back on the syringe. Continue pulling back on the syringe as you continue advancing the needle.

You may identify an actual "popping" sensation as the needle enters the cyst. Continue aspirating: fluid may now be entering the syringe. You may, however, encounter this "popping" sensation but drain no fluid: it is speculated that in such cases, the cyst fluid has drained internally. Continue aspirating until you feel that you have drained all of the cyst's fluid. Once you have completed the aspiration, release the suction before withdrawing the needle from the lesion. Upon completely withdrawing the needle, apply pressure at the puncture site.

If no fluid enters the syringe, pull the needle back to just beneath the patient's skin, then redirect it. Attempt to re-direct the needle two or three times. When you have located the cyst, continue aspirating until no additional fluid enters the syringe. If the fluid becomes bloody, stop the procedure immediately and send any aspirated fluid for cytology.

Follow up
In most cases, FNA will eliminate any symptoms (pain or discomfort) your patient may be experiencing as a result of the breast cyst. When an FNA has yielded clear fluid, and has eliminated both the cyst and any associated symptoms, it is safe to conclude that the cyst was benign and the patient requires no further evaluation at this time. In this case, it is reasonable to instruct your patient to return as needed, should a cyst recur. Patients with one breast cyst, many of whom have fibrocystic breasts, are at increased risk of a cyst recurrence.

An FNA that reveals a non-draining mass, a partially-draining mass, or non-clear fluid indicates the need for further evaluation of the lesion (Ciatto, Goodson, Maygarden, Takeda). Order a mammogram and/or breast ultrasound, and refer the patient for biopsy.