Thyroid Biopsies
Thyroid biopsy is done to find out whether a thyroid nodule is cancer or not, and if cancer, what the type of cancer is. For this, a fine needle aspiration biopsy (FNAB) or trucut biopsy can be used. Both are done with special needles using ultrasound guidance and local anesthesia. In FNAB, a very thin needle is inserted into the nodule and cells are aspirated into a syringe. In trucut biopsy, a cutting needle is inserted into the nodule and cylinders of tissue samples are obtained. In the thyroid, the standart biopsy is FNAB since it is less traumatic and easier to perform. However, FNAB is successful in making a confident diagnosis in about 70% of cases. In the remaining 30%, the result is either “nondiagnostic”, which means that the aspirated cells are not enough, or “inconclusive”, which means that the pathologist can not be sure whether the nodule is cancer or not. In such cases, a second biopsy may be recommended instead of operating the patient directly. Not infrequently however, the second even the third biopsies may also be nondiagnostic or inconclusive, and thus, the patient may be recommended to undergo surgery. Unfortunately, upto 70% of these nodules prove to be benign (not cancer) on pathology, which means that the surgery has been done unnecessarily. For this reason, many authors including us, recommend FNAB plus trucut biopsy as the second and further biopsy procedures. It has been shown that FNAB + trucut biopsy can provide a definitive diagnosis in nearly 90% of these nondiagnostic / inconclusive cases and prevent unnecessary surgeries. However in the thyroid, trucut biopsy is technically more challenging than FNAB and can be performed in only certain centers.
How is FNAB performed?
In thyroid, the recommended biopsy technique is FNAB. However, if FNAB is nondiagnostic, inconclusive or suspicious for cancer, the second/third biopsies should be performed by using a combination of FNAB and trucut biopsy, which yields more accurate and concrete results.
Advantages of trucut biopsy in the thyroid
FNAB obtain cells, which may be difficult to evaluate for the pathologist, but trucut biopsy obtains tissue pieces, which are real tissue samples.
Trucut biopsy provides a more confident diagnosis in nondiagnostic and inconclusive cases.
It can be done under local anesthesia in the same session with FNAB.
If the nodule is cancer, trucut biopsy allows immunochemistry analysis which can tell us what the subtype of cancer is.
Since FNAB is easier and can be done with a very thin needle, it is preferred for the first thyroid biopsy. However, if a second or third biopsies are required due to nondiagnostic or inconclusive results of FNAB, a combined trucut biopsy plus FNAB is generally recommended.
Is trucut biopsy used in other organs?
Trucut (core) biopsy is the standart biopsy technique in most of our organs. It is very commonly used in the breast, liver and other soft tissues. In our center, we use trucut biopsy also in the lung, pancreas, kidney, adrenal gland, lymph nodes, bone and muscle. In the thyroid, we routinely perform FNAB + trucut biopsies when the first FNAB is nondiagnostic, inconclusive or suspicious for malignancy, or when the nodule is too hard in which case it is very difficult to do a FNAB.
If the FNAB is benign can we exclude cancer completely?
Unfortunately, even if the pathology result of the FNAB is benign there is still a small (upto 3%) risk of the nodule being cancer. If the FNAB is non diagnostic the cancer risk may be as high as 5-10%. Conversely, even if the pathology result of the FNAB is definetely cancer there is upto 3% risk of the nodule being not cancer. There is also a considerable variation in pathology results of thyroid nodules among the pathology doctors. While a FNAB specimen can be interpreted as mildly suspicious by one pathologist it may be interpreted as highly suspicious or even benign by another pathologist. In conclusion, pathology results of thyroid nodules may not be very reliable in practice. It is therefore recommended that in thyroid nodules, FNAB results should always be interpreted together with ultrasound features to avoid unnecessary interventions.
| Bethesda’s category | Risk of malignancy (%) if NIFTP = CA |
|---|---|
| Non-diagnostic/unsatisfactory (I) | 5–10 |
| Benign (II) | 0–3 |
| AUS/FLUS (III) | 10–30 |
| FL/SFL (IV) | 25–40 |
| Suspicious for malignancy (V) | 50–75 |
| Malignant (VI) | 97–99 |
What should be done if the result of FNAB is nondiagnostic?
A nondiagnostic biopsy result means that there are not enough cells in the biopsy material to make a diagnosis. In this case, the FNAB must be repeated several weeks later. However, since the insufficient biopsy is generally due to the presence of cyst, blood or hard material inside the nodule, it is quite common that even the second FNAB yields a nondiagnostic result. For this reason, many centers including ours, prefer to perform FNAB + trucut (core) biopsy for the second procedure. Unlike FNAB which tries to suck individual cells into a syringe, trucut biopsy cuts multiple pieces of the nodule, which represent real tissue samples. With combined use of both FNAB and trucut biopsy, the pathologist can make the diagnosis much more accurately and confidently. If the result is cancer, the trucut biopsy materials may also allow better identification of the subtype of the cancer with immunochemistry studies.
What should be done if the result of FNAB is indeterminate or suspicious?
An indeterminate biopsy means that the nodule may be cancer but this is not sure. The pathologist may classify the degree of suspicion into 3 cathegories:
- Mild: AUS/FLUS; Risk of cancer is 15-30%
- Moderate: Follicular neoplasm; Risk of cancer is 25-50%
- High: Suspicious for cancer; Risk of cancer is 65-80%
If a FNAB result falls into one of this categories, this is a difficult situation for both the patient and the doctor because it is not possible to exclude cancer. In this case, doctors may recommend either thyroidectomy or follow-up with repeated biopsies. Unfortunately, both options are not good for the patient because:
If the thyroid is removed surgically, the pathology will not show cancer in most of the cases and the patient will have lost his/her thyroid gland unnecessarily. On the other hand, if the patient remains in the ultrasound follow-up repeat FNABs will be performed with intervals. However, even if all the subsequent biopsies comes as benign, the cancer suspicion will never go away. Thus, the patient will have to live with cancer anxiety for many years. If it proves cancer after many years, then the treatment will have been delayed. Since both options are not optimal for the patient, we prefer treating such indeterminate nodules with cryoablation as we did biopsy-proven thyroid cancers. We believe that this is a good middle way that avoids both extremes. With cryoablation, the suspicious nodule will be killed completely (whether it is cancer or not), the thyroid will be preserved and the patient will be free from cancer anxiety.
CONSULTATION FORM
You can get information on our treatments via phone and e-mail as well as by filling and sending the consultation form below. Please send the reports of your thyroid ultrasound, hormones, scintigraphy and biopsy (if available) via e mail (thyroidgoiter@gmail.com) or whats up ( +90-534-551 0 551). Remember to write clearly your e mail address and phone number so that we can return to you as soon as possible.
Please send separately the results of your thyroid ultrasound, hormones, scintigraphy and biopsy (if available)