What is the role of biopsy in the workup of follicular thyroid carcinoma (FTC)?

Updated: Jun 18, 2020
  • Author: Luigi Santacroce, MD; Chief Editor: Neetu Radhakrishnan, MD  more...
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Fine-needle aspiration biopsy (FNAB) is considered the best first-line diagnostic procedure for a thyroid nodule; it is a safe and minimally invasive test. It is the required procedure for the diagnostic evaluation of the classic solitary thyroid nodule.

Local anesthesia is administered at the puncture site, and a 21G or 23G aspiration biopsy needle is guided into the mass. The nodule is held with the fingers of the left hand while a needle is introduced through the skin into the nodule with the right hand.

After aspiration, the material is placed on a glass slide, fixed with alcohol-acetone, and stained according to the technique of Papanicolaou.

Accuracy of FNAB is better than that of any other test for uninodular lesions. Sensitivity of the procedure is near 80%, specificity is near 100%, and errors can be diminished using ultrasound guidance. False-negative and false-positive results occur less than 6% of the time.

A cytologist could experience difficulty in distinguishing some benign cellular adenomas from their malignant counterparts (ie, follicular and Hürthle cell adenomas from carcinomas).

Thyroid biopsy could be performed using the classic Tru-Cut or Vim-Silverman needles, but FNAB is preferable. Patients comply best with FNAB.

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