Understanding Thyroid Nodules and the Biopsy Process
By Medical Correspondent Dr. Taehwan Kim, Otolaryngologist | Source: Hidoc
Thyroid nodules are a common discovery during health checkups, often leading to concerns about the possibility of cancer. This article aims to provide clarity on what thyroid nodules are, the criteria for biopsy, and the biopsy methods employed.
What are Thyroid Nodules?
A thyroid nodule refers to abnormal growth in the tissue of the thyroid gland, with a prevalence of 20-40% in adults, increasing with age.
When is a Biopsy Necessary?
Not all nodules require biopsy; decisions are made based on ultrasound findings, including size, aspect, and shape of the nodule.
Thyroid Grades Differentiated on Ultrasound
The classification of thyroid nodules, based on ultrasound findings, ranges from stages 2 to 5, impacting the likelihood of malignancy.
- Stage 2: Indicates a cyst or lump, often benign and requiring follow-up observation.
- Stage 3: Partial liquid component with no malignancy suspicion.
- Stage 4: Partial cyst or nodule with conditions raising suspicion of malignancy.
- Stage 5: Represents a solid, hypoechoic nodule, highly suspicious for malignancy.
Biopsy Methods and Results
Biopsies are conducted through fine needle aspiration tests and total biopsies, with results classified into stages 1 to 6 based on the Bethesda system, guiding further action.
Understanding the complexities of thyroid nodules and biopsy processes can be daunting. However, adherence to established guidelines is essential to alleviate concerns and inform appropriate treatment decisions.
Written by Dr. Taehwan Kim, Otolaryngologist | Source: Hidoc
Expert opinion may vary from Hidoc’s viewpoints. Copyright © Hidoc, all rights reserved. No reproduction without permission.
Hidoc Medical Correspondent Kim Tae-hwanㅣSource: Hidoc
Nowadays, thyroid ultrasound is often performed during health checkups, so many small thyroid nodules or cysts are discovered. Patients are often worried about cancer when they only hear about ‘thyroid nodule’ and ask, “I heard there is a thyroid nodule, but isn’t it thyroid cancer?” So, I would like to talk about what a thyroid nodule is, when a biopsy should be performed, and what the biopsy method is.
What is a thyroid nodule?
A thyroid nodule is a general term for specific thyroid tissue that overgrows or grows in a different shape than normal thyroid tissue. Thyroid nodules are found in 20-40% of adults, and their incidence tends to increase with age.
When is a biopsy done?
Should all nodules be tested? Not all nodules are biopsied. By looking at the ultrasound and looking at the size, aspect, and shape of the nodule, a decision is made whether to have a biopsy.
Thyroid grades differentiated on ultrasound
Through thyroid ultrasound, the shape of thyroid nodules is classified into stages 2 to 5.
Distinct thyroid grades on ultrasoundㅣSource: 2016 Korea Journal of Radiology
△ Stage 2: Cyst or lump. In this case, there is a very high possibility that it will be benign, and if it is not large, follow-up observation is often necessary.
Thyroid cystㅣSource: Breath Samsung ENT Clinic
△ Stage 3: When there is a partial liquid component or nodule, but there is no finding to suspect malignancy.
△ Stage 4: It is a partial cyst or nodule shape, but there are conditions that may lead to suspicion of malignancy.
△ Stage 5: This is a solid, hypoechoic nodule that appears suspicious for malignancy.
What findings suggest malignancy?
This is when the border is unclear, there is microcalcification, or it is long vertical. As stage 2 progresses, the likelihood of malignancy decreases, but as stage 5 increases, the possibility of malignancy increases, so a biopsy may be necessary even if the size is small.
Thyroid nodule is suspected to be malignantㅣSource: Samsung Breath, Otolaryngology Clinic
How to perform a biopsy?
There are two methods for thyroid nodule biopsy. This is a fine needle aspiration test and a total biopsy. As most nodules that occur in the thyroid gland are small in size, a fine needle aspiration test is performed, where tissue is aspirated with a thin needle. This is a method of removing as many cells as possible from the nodule using the needle used to collect blood and check for the presence or absence of malignant cells. It is generally not a dangerous test because it is performed while looking at an ultrasound to check in real time if the needle is inserted properly, and because it is performed under local anesthesia, there is almost no pain.
On the other hand, if the nodule is large or a follicular tumor is suspected, a whole biopsy can be performed. A complete biopsy has the advantage of collecting more tissue using a thicker needle than a fine needle aspiration test and allowing for special immunosuppression.
How do the biopsy results come out?
When a fine needle aspiration test is performed, it is classified into stages 1 to 6 through the Bethesda system established by the Society of Pathologists.
Stages 1 to 6 classified by the Bethesda systemㅣSource: Samsung Breath, Otolaryngology Clinic
Stage 1 often requires re-examination because not enough cells are found, and stage 2 is when only positive cells are found, so only follow-up observation is required. Stage 3 is when atypical cells appear, which are not malignant but also not benign, so the possibility of malignancy is around 15%. Typically, a re-examination is required. Stage 4 is when a follicular tumor appears and a diagnostic thyroidectomy is performed, and stages 5 and 6 are when malignant cells are seen.
Because the number of cases for thyroid ultrasound and biopsy are so varied and their interpretation is not straightforward, it is difficult to make a decision from the patient’s perspective. However, as mentioned above, there are guidelines for every situation, so if you think about treatment based on principles, you will be able to alleviate some of your concerns.
Written by = Hidoc Medical Correspondent Dr. Taehwan Kim (ENT Specialist)
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