Thyroid biopsy is performed to determine whether the nodule or nodules detected in the thyroid gland are benign or malignant. The most common biopsy in the thyroid is fine-needle aspiration biopsy (FNAB). In FNAB, a very thin needle is placed from the skin into the nodule and by applying a vacuum with the syringe, cells from various parts of the nodule are sucked into the syringe. These cells are then spread on small glasses and examined by a pathologist.
FNAB has an accuracy rate of over 90% and is now the standard biopsy method for the evaluation of thyroid nodules. However, FNAB is a procedure that needs to be implemented carefully and accurately; During FNAB, cells should be taken from all suspicious nodules and from different parts of each nodule, if possible. In addition, special attention should be paid to suck too much blood into the injector. A FNAB that is inappropriately done may cause a cancerous nodule to be overlooked or yield a suspicious result that may cause unnecessary surgery in a patient without cancer.
After FNAB, it can be usually determined whether the nodule is benign or cancerous. However, in 5 to 10% of patients, despite a high quality FNAB, the pathologist cannot make a definitive diagnosis or the result may be said to be suspicious. In such cases, the patient may be recommended surgery, but this is not an acceptable approach. In such patients, a repeat biopsy should be done. The second biopsy can be performed as FNAB. However, in order to prevent an unnecessary operation, it may be more appropriate to do the second biopsy as trucut (core) biopsy instead of FNAB. Sometimes, both trucut and FNAB can be done in the same session, which is our strategy in most repeat thyroid biopsies. When these methods are used, in more than half of the patients with cancer suspicion in the first biopsy, it can be shown that there is no cancer, and unnecessary operations can be prevented.
Video information: "Thyroid fine needle aspiration biopsy"