When someone discovers a thyroid nodule, he or she might be worried, particularly when the doctor suggests a biopsy. After your thyroid biopsy, a frequent question patients have is: What is my Bethesda score? The Bethesda System is used to report the results of a thyroid fine-needle aspiration (FNA) or FNAC. It categorises the results of the biopsy into six categories and helps doctors understand the chances of malignancy and their next steps. The present guidelines are based on the 2023 Bethesda System for Reporting Thyroid Cytopathology.
The standardized reporting system is based on what the pathologist observes in the cells obtained from the thyroid nodule. Dr. Nikunj Jain, the Co-Founder and HOD – Nuclear Medicine, provides evaluation and nuclear medicine services at Molecular Diagnostics and Therapy. The analysis to be conducted depends on what symptoms the patient is presenting, results of the Ultrasound exam, medical history, and a clinical evaluation.
What Is the Bethesda System?
The Bethesda System provides a standard way of reporting thyroid FNAC results. Since different laboratories used varying variables and terminology to describe the same phenomena, the report is categorized into one of six categories to facilitate communication of their data:
Nondiagnostic
Benign
Atypia of Undetermined Significance
Follicular Neoplasm
Suspicious for Malignancy
Malignant
A risk of malignancy is associated with each type, although the risk may differ depending on the clinical context, ultrasound characteristics, lab characteristics, and eventual surgery of the nodule. Therefore, the Bethesda category should always be examined in conjunction with the thyroid ultrasound and the patient's clinical information.
Why Is Bethesda Classification Used?
The occurrence of thyroid nodules is quite common, and the majority are non-cancerous. Ultrasound is usually utilized to figure out the appearance of a nodule and whether or not it's wise to have a biopsy. In FNAC, the cells within a thyroid nodule are sampled using a thin needle. These cells are analyzed under a microscope by a pathologist and given the Bethesda category. This can assist the treating physician in determining if the patient may require observation, repeat serum test, further molecular testing, surgery, or any other means of evaluation.
Bethesda Category I: Nondiagnostic
A Bethesda I result indicates the specimen was non-diagnostic or insufficient to establish a definitive cytologic diagnosis. This does not mean that the nodule is cancerous. This is merely because insufficient information from the biopsy was available for diagnosis. Depending upon the ultrasound appearance and other clinical findings, the physician may suggest further use of FNAC or some other appropriate method.
Bethesda Category II: Benign
If your interpretation of the Bethesda comes back as "benign" (II), it means that the cells you were examined for were not found to be cancerous. This is usually deemed to be a low-risk category. Bethesda II is considered a benign category and has a low estimated risk of malignancy. The exact risk depends on the Bethesda edition, clinical population, and how malignancy risk is calculated, so the category should be interpreted together with the ultrasound and clinical findings. A benign result does not necessarily mean that the nodule never changes. Further ultrasound examinations may be suggested based on the size, appearance, and other characteristics of the nodule.
Bethesda Category III: Atypia of Undetermined Significance
Bethesda III is an indeterminate category. It implies cells that exhibit abnormal characteristics, but not enough to say definitely that the nodule is or isn't definitely benign or malignant. Within this group, the Bethesda System 2023 classifies it into two subcategories, depending on the type of atypia. An elevated diagnosis of “Bethesda III” does not necessarily indicate thyroid cancer. The doctor may suggest repeating FNA procedures, molecular tests, further observation, or surgery, depending on the details of findings, ultrasound appearance, the patient's circumstances, and local practice.
Bethesda Category IV: Follicular Neoplasm
A follicular neoplasm or a related lesion that has a follicular pattern is suggested by Bethesda IV. The one significant disadvantage of FNAC is that when lesions have a follicular pattern, examination of individual cells is not sufficient in some such lesions to differentiate between benignity and malignancy. This may be based on invasion that can only be determined from a more thorough examination of the tissue. As a result, Bethesda IV does not signify the nodule is definitely cancerous. Suggests possibly some additional testing, molecular testing, surgery, or other evaluation based on the case.
Bethesda Category V: Suspicious for Malignancy
The “Bethesda V” diagnosis indicates the presence of cells with traits that suggest cancer, but that do not match all of the characteristics needed for a clear diagnosis of malignancy. This is the next higher category than the benign and indeterminate lower categories in terms of the risk of malignancy. Depending on the biopsy, ultrasound, size of the nodule, patient history, and more, the treating practice might recommend more tests or surgery.
Bethesda Category VI: Malignant
If the results of the cytology are deemed to be consistent with malignancy, the result is referred to as Bethesda VI. Papillary thyroid cancer is the most prevalent type of thyroid cancer detected on thyroid FNAC. A malignant cytology result usually warrants further evaluation and treatment planning by the appropriate team/specialists. Treatment varies according to the type and extent of thyroid malignancy and the size, location, and whether or not lymph nodes are involved, plus additional factors.
What Does the Bethesda Number Mean for Cancer Risk?
The Bethesda category gives doctors an estimate of the likelihood of malignancy, but it should not be treated as an individual patient's exact probability of having cancer. The 2023 Bethesda System updated the estimated risks associated with its six categories and provides both average risks and expected ranges. These estimates can vary depending on factors such as whether the nodule was selected for surgery and the clinical population being studied.
For this reason, patients should avoid interpreting the Bethesda number alone. For example, a Bethesda III or IV result does not mean that cancer is confirmed. Similarly, a benign result should still be interpreted alongside the ultrasound and clinical findings.
How Is the Bethesda Result Used With Thyroid Ultrasound?
FNAC and ultrasound provide different types of information. Ultrasound shows the structure and appearance of the thyroid nodule. It can describe features such as its size, composition, margins, shape, echogenicity, and calcifications. FNAC examines the cells obtained from the nodule. Doctors consider both sets of information when deciding what should happen next. A Bethesda result therefore should not be interpreted separately from the ultrasound report.
What Happens After a Bethesda Result?
The next step depends on the Bethesda category and the patient's overall clinical picture. For a benign result, doctors may recommend follow-up ultrasound. A nondiagnostic result may require a repeat biopsy. Indeterminate categories such as Bethesda III or IV may lead to repeat FNAC, molecular testing, surveillance, or surgery depending on the individual case. Suspicious or malignant results generally require further specialist evaluation and treatment planning. There is no single next step that is appropriate for every patient.
Can Molecular Testing Be Used for Indeterminate Results?
In selected patients with indeterminate thyroid biopsy results, molecular testing may provide additional information. These tests look for specific genetic changes or molecular patterns associated with thyroid nodules. They may help doctors further assess some indeterminate nodules and support decisions about observation or surgery. However, molecular testing is not necessary for every patient, and its use depends on the individual case and availability.
How Long Does a Thyroid Biopsy Report Take?
Thyroid FNAC results can take several days to become available. The American Thyroid Association notes that results may take anywhere from a few days to about two weeks, depending on the situation and testing process. If additional testing is required, such as molecular testing, the overall reporting time may be longer.
What Should You Do If Your Report Says Bethesda III or IV?
Seeing an indeterminate Bethesda category can be stressful, but it does not automatically mean that you have thyroid cancer. The next step should be discussed with your doctor. They may review your ultrasound findings, symptoms, medical history, thyroid blood tests, and the details of the cytology report before recommending repeat FNAC, molecular testing, monitoring, or surgery. Avoid making treatment decisions based only on the Bethesda number.
Thyroid Evaluation at Molecular Diagnostics and Therapy
At Molecular Diagnostics and Therapy, thyroid evaluation and nuclear medicine services are provided under the guidance of Dr. Nikunj Jain, Co-Founder and HOD – Nuclear Medicine. Dr. Nikunj Jain has more than 18 years of experience in nuclear medicine and has performed more than 75,000 PET-CT scans along with extensive gamma scans.
Thyroid evaluation may involve different investigations depending on the patient's symptoms and clinical findings. Ultrasound, blood tests, FNAC, and other investigations may provide complementary information when clinically indicated. The purpose of these investigations is to help the treating doctor understand the thyroid condition and determine the appropriate next step for the patient.
Conclusion
To report and interpret the outcomes of thyroid biopsy, the Bethesda System categorizes FNAC results into 6 typical groups. These vary all the way from Nondiagnostic and Benign to Suspicious for Malignancy and Malignant, with indeterminate in between. The Bethesda result cannot be taken in isolation and is not just a number. The results of the biopsy, thyroid ultrasound, blood tests, medical history, and symptoms are all very important components of the clinical decision.
Your doctor might look at your thyroid biopsy report and say it or show it to you as a reference for the six diagnostic categories (Bethesda I, Bethesda II, Bethesda III, Bethesda IV, Bethesda V, and Bethesda VI). Talking with your doctor about your biopsy report can more fully educate you about its contents and what to expect from your next follow-up appointment. At Molecular Diagnostics and Therapy, thyroid and nuclear medicine services are provided by Dr. Nikunj Jain and the expert team with investigations necessary according to clinical requirements.