A Fine Needle Aspiration (FNA) Biopsy

Reasons, Procedure, and Side Effects

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A fine needle aspiration is one method of doing a lung biopsy to confirm or rule out the presence of a lung cancer. Of the different procedures available, a fine needle biopsy is the least invasive, but is not always possible and may sometimes obtain insufficient tissue for testing. We will talk about the procedure, when it may be done, and the potential side effects.

A fine needle aspiration of a suspicious spot in the lungs is also referred to as a percutaneous biopsy or a transthoracic biopsy.


A fine needle aspiration biopsy (FNA biopsy) is a test done to see if a tumor is benign (non-cancerous) or malignant (cancerous). In the procedure, a fine (but long) needle is inserted through the surface of the skin and into a tumor. A small sample is aspirated and the needle removed.

Reasons to Do an FNA

If your doctor has found a tumor on a chest x-ray or CT scan, she may have some idea whether or not the nodule or mass is cancer. Yet benign and malignant tumors can look very similar on a scan. An FNA may be done to evaluate:

  • A lung nodule (defined as a spot in the lung that is 3 centimeters in diameter or less)
  • A lung mass


A fine needle aspiration (FNA) is done by inserting a thin needle from the outside of the body into a tumor and removing cells that can be evaluated under the microscope. A pathologist looks at the cells to see if the suspicious tumor is cancer and if it is cancer, what type of cancer.

With lung cancer, the needle is inserted into the chest through the skin on the chest and into a tumor which is often found on a CT scan of the chest. Doctors can make sure the needle goes to the right part of the lung by watching it with a CT scanner. If there is a lesion that is more easily approached than those in the lung (for example, lymph nodes that can be felt), FNA may be used on that site instead of the lungs.


FNA is less invasive than an open biopsy of the lung, one through an incision into the chest. Learn more about the different biopsy techniques which may be used to diagnose lung cancer.

In a 2016 study, it was found that FNA was successful in retrieving a sample sufficient to adequately diagnosis lung cancer in 91 percent of people on which the procedure was performed. It's important to note, however, that this procedure is not possible for all tumors, and may not be an option for tumors at some locations in the lungs.


Just as there are advantages, there are a few disadvantages to FNA.

False Positives

In the above-mentioned study, it was found that FNA was very sensitive in diagnosing in lung cancer. That said, FNA can sometimes deliver false positive results, in other words, finding a cancer which is actually not there. In this study, it was found that specificity of the technique was 81 percent, meaning that around 20 percent of the time an incorrect diagnosis of cancer may be made. This is one important reason why doctors usually use a combination of tests to diagnose lung cancer (unless a large specimen can be obtained in an open biopsy.)

Insufficient Testing

Though the study above found that sufficient tissue to make a diagnosis was present 91 percent of the time, this still means that almost 10 percent of people will have an inadequate sample. In addition to having to undergo another procedure, this can lead to a delay in diagnosis as well as treatment. In addition, more testing (such as next generation sequencing) is recommended (at least with non-small cell lung cancer) than even a few short years ago, and FNA may not provide enough tissue to perform these tests; tests that may lead to effective therapies.


There are several complications that are possible with an FNA, but in general, this procedure is less invasive and safer than other methods of getting a specimen for a biopsy.

  • Bleeding: You doctor will talk to you about any medications you take that can increase bleeding time. It's important to note that some nutritional supplements and herbal preparations can increase bleeding time and to let your doctor know about any over-the-counter medications or supplements you are using. Bleeding (pulmonary hemorrhage) most commonly occurs in elderly people.
  • Pneumothorax: An air leak is a common complication, with some degree of air leak occurring in around half of the people who have this procedure. If a pneumothorax occurs, a chest tube may need to be inserted. At times the chest tube will need to be left in place for a period of time until your lung re-expands and the pneumothorax has resolved.
  • Tumor seeding: There is a hypothetical risk that FNA could result in tumor seeding. The thought is that some of the cells removed through the biopsy could be left behind along the course of the needle as it is removed. If this occurred, the cells could grow in the spot in which they were left behind and start a new tumor (metastasis). While this potential has not been studied to the same degree as with breast cancer, it has been found that core biopsies with breast cancer may lead to seeding.

Getting Your Results

Talk to your doctor at the time of your biopsy and ask when she will expect the results to be available. Some doctors will call you by phone with results, whereas others will ask that you come to the office to discuss results and further steps.

Also Known As: needle aspiration biopsy (NAB), fine needle aspiration cytology (FNAC)

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