What is the role of fine-needle aspiration biopsy (FNAB) in the evaluation of thyroid cancer?

Updated: May 09, 2018
  • Author: Pramod K Sharma, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

FNAB is the most important diagnostic tool in evaluating thyroid nodules and should be the first intervention. The technique is inexpensive and easy to perform, and it causes few complications.

To perform FNAB, comfortably position both the patient and the physician. Extend the patient's neck slightly and palpate the nodule with the nondominant hand. Clean the skin with alcohol and infiltrate the area with local anesthesia. Place a 21- to 25-gauge needle on the end of a syringe. Many physicians use trigger-style aspirating handles on the syringe. Introduce 2 mL of air into the syringe, and place the needle into the skin. Apply negative pressure to the syringe, and pass the needle through the nodule, which is identified by using the nondominant hand. After several passes, release the negative pressure, and withdraw the needle. Use the air remaining in the syringe to expel the specimen from the hub and needle onto a glass slide or into cytologic solution for a cell block. Fix the slide in alcohol for Papanicolaou and hematoxylin-eosin staining. Some slides can be air dried and stained with Romanowsky stain (Diff-Quick).

Successful diagnosis by the cytologist depends on accurate sampling of the nodule and specimen cellularity. For this reason, several authors recommend performing at least 3 aspirations to ensure adequacy of the specimen and to minimize false-negative results. Ultrasonographic guidance can help to increase the accuracy of FNAB. Danese et al report increased false-negative rates with palpation FNAB compared with ultrasonography-guided FNAB.


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