Understanding Thyroid Nodules: A Complete Guide to Diagnosis and Management

Table of Contents

• Key Points
• Background: Why Thyroid Nodules Matter
• How This Review Was Conducted
• Thyroid Ultrasound: The Gold Standard
• Risk Stratification Systems: Sorting Nodules by Danger
• CT and MRI: Limited but Useful Roles
• PET/CT Scans and Incidental Findings
• Nuclear Imaging (Scintigraphy) for "Hot" and "Cold" Nodules
• Fine-Needle Aspiration Biopsy (FNAB)
• Molecular Testing: Reading the Genetic Signature
• Management and Follow-Up
• When Surgery Is Needed
• Nonsurgical Treatment Options
• What This Means for Patients
• Limitations of the Evidence
• Practical Recommendations
• Frequently Asked Questions
• Source Information

Key Points

• Most thyroid nodules are benign, with a malignancy rate under 5% in most series, and can usually be safely monitored rather than removed.
• Thyroid ultrasound is the gold standard for assessing nodule appearance, and standardized risk systems like TI-RADS or ATA categories help decide if biopsy is needed.
• Biopsy of nodules smaller than 1 cm is generally not automatic; active surveillance with repeat imaging is often preferred for small, suspicious nodules.
• Molecular testing of indeterminate biopsy samples can reduce the need for diagnostic surgery, though using results to guide therapy is not yet standard of care.
• For benign nodules causing symptoms or cosmetic concern, nonsurgical options such as ethanol ablation and thermal techniques are increasingly available.

Background: Why Thyroid Nodules Matter

Thyroid nodules (TN, lumps or growths within the butterfly-shaped thyroid gland in the neck) are very common. Between 20% and 60% of prospectively and randomly selected patients have at least one, according to the review. That means roughly 1 in 5 to 3 in 5 adults walking into a clinic could have a nodule if you looked carefully enough.

Most of these nodules never cause symptoms. Some are found because a patient or doctor feels them. But today most are discovered incidentally. This means they show up on an imaging scan done for an entirely unrelated reason, such as a CT scan of the neck or chest.

The reassuring news is that the overwhelming majority are benign (non-cancerous). Even as the number of diagnosed thyroid cancers has risen in recent decades, the rate of malignancy (cancer) in thyroid nodules is less than 5% in general, with most series citing a range of 7% to 15% for nodules that come to medical attention. The rise in thyroid cancer diagnoses is largely explained by increased imaging picking up small, low-risk tumors that would never have caused harm.

The purpose of evaluating a nodule is twofold. First, doctors want to determine whether it is benign or malignant. Second, when a nodule is benign but causing troublesome local symptoms, they want to establish whether an intervention could relieve those symptoms. Routine population screening for thyroid nodules is not recommended. However, particular attention should be paid to people with known risk factors for thyroid cancer, which include:

• Childhood exposure to ionizing radiation (such as radiation therapy to the head or neck)
• Variations in dietary iodine intake
• Inherited genetic syndromes associated with thyroid cancer include familial adenomatous polyposis, Carney complex, Cowden syndrome, and Peutz-Jeghers syndrome. They also include PTEN hamartoma tumor syndrome, a condition caused by mutations in the PTEN gene, leading to multiple benign growths.
• A family history of medullary thyroid cancer (a rare thyroid cancer arising from hormone-producing C cells) or multiple endocrine neoplasia syndrome (MEN, a hereditary condition affecting several hormone glands)

How This Review Was Conducted

The authors conducted a structured search of PubMed and Medline for articles on the epidemiology, diagnosis, and management of thyroid nodules. PubMed and Medline are two large databases of medical research. The authors searched for articles published over the past 5 years. They reviewed 135 articles and also examined the reference lists of those papers to find additional pertinent studies. This is known as a narrative review. A narrative review does not pool data statistically the way a meta-analysis does. Instead, it synthesizes the best available evidence and expert guidance into a practical framework.

Thyroid Ultrasound: The Gold Standard

Thyroid ultrasound (US, a procedure that uses high-frequency sound waves to create real-time images of the gland) is the gold standard for assessing nodule morphology (shape, structure, and appearance). It is generally recommended for any nodule found either by physical examination or through another imaging test.

Because ultrasound technology has improved substantially, doctors can now give a detailed morphologic description of thyroid anatomy. Several specific features seen on ultrasound have been linked to a higher risk of thyroid cancer. These include:

• Size of the nodule
• Echogenicity — how dark the nodule appears compared with surrounding tissue (hypoechoic, meaning darker, is more concerning)
• Nodule border — irregular or lobulated borders raise suspicion
• Vascular pattern — how blood flows through the nodule
• Nodule shape — a nodule that is "taller than wide" on a transverse view is suspicious
• Tissue stiffness, measured by elastography (a technique that assesses how firm or hard tissue feels to sound waves)
• Microcalcifications or macrocalcifications — tiny or larger calcium deposits within the nodule
• Abnormal-appearing cervical lymph nodes (the lymph nodes in the neck)

Here is the critical caveat: no single ultrasound feature is accurate enough on its own to diagnose thyroid cancer. Each one has a broad range of sensitivity (how often it correctly identifies cancer) and specificity (how often it correctly rules cancer out). Because of this, doctors developed risk assessment strategies that combine multiple features to estimate the probability of malignancy and decide whether further testing is warranted.

Risk Stratification Systems: Sorting Nodules by Danger

In 2017, the American College of Radiology issued a standardized system called TI-RADS (Thyroid Imaging, Reporting and Data System). It uses a point-scoring method that takes into account nodule composition, echogenicity, shape, size, margins, and the presence of echogenic foci (bright spots on ultrasound). The recommendation for fine-needle aspiration biopsy (FNAB, a procedure to sample cells with a thin needle) is based on combining the TI-RADS score with the nodule's size.

The American Thyroid Association (ATA) system works a bit differently. It relies on recognizing sonographic patterns and classifying nodules into five categories with associated cancer risk ranges:

• Benign — less than 1% risk
• Very low suspicion — less than 3% risk
• Low suspicion — 5% to 10% risk
• Intermediate suspicion — 10% to 20% risk
• High suspicion — greater than 70% to 90% risk

Both systems recommend against automatically biopsying nodules smaller than 1 cm and instead lean toward active surveillance (careful monitoring with repeat imaging) for these small, suspicious nodules.

Similar scoring systems have been issued by other professional bodies. These include the Korean Society of Thyroid Radiology (K-TIRADS) and the European Thyroid Association (EU-TIRADS). They also include the American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi (AACE/ACE/AME). The table below summarizes the biopsy size thresholds each system recommends:

• ACR TI-RADS: Biopsy at 2.5 cm (mildly suspicious), 1.5 cm (moderately suspicious), or 1.0 cm (highly suspicious)
• ATA: Consider biopsy at 2 cm (low suspicion), 1.5 cm (mildly suspicious), or 1.0 cm (intermediate or high suspicion)
• AACE/ACE/AME: Biopsy at 2.0 cm (low risk), 2.0 cm plus other risk factors (intermediate), or 1.0 cm and selectively 0.5 cm (high risk, 50%–90% cancer risk)
• EU-TIRADS: Biopsy at 2 cm (low risk, 2%–4%), 1.5 cm (intermediate, 6%–17%), or 1.0 cm (high risk, 26%–87%)
• K-TIRADS: Biopsy at 2 cm (low, less than 1%–3%), 1.5 cm (intermediate, 3%–15%), or 1.0 cm with selective 0.5 cm biopsy for high suspicion (15%–50%, up to greater than 60%)

Where "other risk" is referenced, this means factors such as increasing nodule size, previous head and neck radiation exposure, and family history of thyroid cancer. It also means previous thyroid surgery or minimally invasive ablation therapy.

CT and MRI: Limited but Useful Roles

CT (computed tomography, a type of X-ray scan) and MRI (magnetic resonance imaging) have limited roles in the routine evaluation of thyroid nodules. They are generally reserved for patients with a clinical suggestion of advanced thyroid malignancy. They are also used for presurgical planning and for assessment of central- and lateral-compartment cervical lymph nodes. They are also used to evaluate whether a tumor involves the airway, digestive tract, or blood vessels.

PET/CT Scans and Incidental Findings

PET/CT (positron emission tomography combined with CT, a scan that highlights metabolically active tissue) sometimes picks up thyroid nodules by accident. Incidental thyroid nodules appear in 1% to 2% of all 18F-FDG PET/CT scans (FDG is a radioactive sugar tracer).

The reported rate of cytology-proven malignancy in these incidentally found nodules ranges widely, from 24% to 58.2%. By contrast, diffuse uptake throughout the thyroid (rather than a single spot) is associated with a much lower malignancy rate of 4.4%.

A meta-analysis of 18 studies involving 55,160 patients found that 1% of cases had thyroid incidentalomas detected on PET, with a 33.2% incidence of malignancy. Papillary thyroid cancer (the most common type of thyroid cancer) accounted for 82.2% of those cases.

Despite this increased detection, newly diagnosed incidental thyroid cancers do not appear to affect mortality. In a retrospective review of 45,000 PET/CT scans, the incidence of thyroid cancer among thyroid incidentalomas was 36%. However, over a median follow-up of 24 months, most deaths (181) were related to the primary malignancy that prompted the scan—not to thyroid cancer. This finding reinforces that many of these detected cancers are indolent (slow-growing and unlikely to cause harm).

Nuclear Imaging (Scintigraphy) for "Hot" and "Cold" Nodules

A patient may have a newly diagnosed thyroid nodule and a subnormal thyroid-stimulating hormone (TSH) level. TSH is a pituitary hormone that tells the thyroid how hard to work. The next step is typically a radioactive iodine uptake scan and thyroid scan to determine whether the nodule is hyperfunctioning (overactive). In such cases, ultrasound can still be used to check for other nonfunctioning nodules that might need separate evaluation. Of note, small hyperfunctioning nodules may not cause full TSH suppression, so if clinically indicated, scintigraphy should still be considered when TSH is at the low end of normal.

Before ultrasound became widespread, scintigraphy-based thyroid imaging played a central role in evaluating nodules and multinodular goiters. Multinodular goiters are enlarged thyroids with multiple nodules. This imaging used 99mTc-pertechnetate (TcO4) and radioactive iodine (131I and 123I). In the United States, nuclear thyroid imaging for nodularity is now primarily reserved for cases with clear TSH suppression and suspected thyrotoxicosis (excess thyroid hormone). In other parts of the world, including Europe, it is used more commonly.

An important nuance: "cold" nodules on scintigraphy (areas that take up little or no tracer) can represent malignancy, but many benign nodules also appear low-functioning. In contrast, "hot" hyperfunctioning nodules are rarely malignant.

A 1981 review of 6 articles found the following thyroid cancer rates associated with each scintigraphy finding: hypofunctioning nodules, 16%; normofunctioning nodules, 29%; and hyperfunctioning nodules, 24%.

There can be a discrepancy between 99mTc uptake and 131I uptake by cancerous nodules, particularly in follicular thyroid cancer (a cancer that arises from the thyroid's hormone-producing cells). Some nodules took up 99mTc but appeared "cold" on 131I imaging. Because of this, 123I is preferred over 99mTc as the imaging agent when scintigraphy is used to assess nodules.

A recent study compared 123I scintigraphy with thyroid ultrasound for deciding who should be referred for biopsy. The two approaches gave concordant (agreeing) recommendations in 79.4% of cases. Discordant recommendations included an ultrasound-based referral for biopsy of functional nodules in 3.8% of cases, and a 123I-based recommendation for biopsy in 7.9%—either when there was no nodule seen on ultrasound or when the nodule did not meet ultrasound criteria for biopsy.

The American Thyroid Association's 2015 guidelines recommend limited use of thyroid scintigraphy, primarily for cases with suppressed TSH. The reasoning is that finding an autonomous (independently overactive) nodule would eliminate the need for biopsy of that nodule. The exception is the rare situations when malignancy is suspected based on ultrasound appearance. The European Association of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging have published joint guidelines. These guidelines note potential uses for thyroid scintigraphy. One use is evaluating a multinodular goiter for a hyperfunctional "hot" nodule that does not need biopsy. Another is evaluating suspicious hypofunctional "cold" areas that may need biopsy. A third is evaluating nodules with indeterminate biopsy results to identify an autonomous functioning nodule.

TSH suppression from autonomous nodules can vary depending on local dietary iodine intake. Autonomous nodules with TSH levels in the low reference range have been found in populations with lower dietary iodine intake. Scintigraphy has also been proposed as a way to identify and closely monitor autonomous nodules early, before they develop into full-blown thyrotoxicosis. In summary, although scintigraphy is not expected to be necessary for most patients with normal thyroid function, local factors may influence the decision to use it.

Fine-Needle Aspiration Biopsy (FNAB)

A thyroid nodule that meets morphologic criteria on ultrasound should be further assessed by cytology (microscopic examination of cells) obtained through biopsy. Thyroid FNAB is a straightforward outpatient procedure performed under ultrasound guidance, typically using 27- and 25-gauge sterile needles. Local anesthesia is sometimes used, though its benefit for reducing patient discomfort with fine needles has been questioned in the literature. Complications are uncommon and include local bruising and, rarely, hematoma (a collection of blood).

Studies examining the relationship between nodule size and FNAB accuracy have produced conflicting results. FNAB accuracy ranges from 60% to 94% for nodules smaller than 1 cm and from 80.3% to 87.5% for nodules larger than 4 cm.

Core needle biopsy uses a slightly larger needle to obtain a small tissue core. Core needle biopsy is currently considered when FNAB yields nondiagnostic results. It is also considered when thyroid lymphoma or anaplastic thyroid cancer is suspected. Anaplastic thyroid cancer is a rare, aggressive cancer. The Korean Society of Thyroid Radiology recommends core needle biopsy as a first-line alternative to FNAB. However, core needle biopsy has been associated with a higher rate of complications. These complications include post-biopsy hematomas, bleeding from the incision site, pain, and infections. They also include transient hemoptysis (coughing up blood) and nerve injuries.

Under the Bethesda criteria (the standard system for reporting thyroid cytology findings), nodules are classified into 6 categories. Bethesda categories III and IV include nodules with indeterminate cytology (cells that don't look clearly benign or clearly cancerous), with associated malignancy risks of 10% to 30% and 25% to 40%, respectively. Historically, these cases required surgical removal to achieve a definitive diagnosis—leading to a significant number of unnecessary surgeries.

Molecular Testing: Reading the Genetic Signature

The introduction of molecular testing of cytology samples has greatly reduced the need for surgical intervention in indeterminate cases. These tests identify genomic alterations (changes in DNA and RNA) associated with thyroid malignancy, such as gene mutations, gene fusions, and differences in RNA and microRNA expression.

The most prevalent commercially available molecular tests for assessing thyroid nodule malignancy risk include:

• Afirma Genomic Sequencing Classifier with add-on Xpression Atlas
• ThyroSeq 3.0
• ThyGenX/ThyraMIR
• Rosetta GX Reveal

Mutations identified by these tests may help guide management. For example, the presence of both BRAF V600E and TERT C228T mutations in papillary thyroid cancer appears to be associated with poorer outcomes and so may carry prognostic and management-decision value. Conversely, the RAS mutation has been identified in benign nodules, follicular adenomas (benign growths), noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP, a very low-risk tumor), papillary thyroid cancer (classic, follicular variant, and poorly differentiated), and anaplastic and medullary thyroid cancers. In other words, finding RAS alone is not a definitive cancer diagnosis.

At present, using molecular marker results to guide therapeutic recommendations has not yet been proven to improve outcomes. These recommendations include the extent of surgery or whether to give radioactive iodine. This approach is not considered the standard of care. The relatively high cost may also be a limiting factor.

Management and Follow-Up

The authors present an algorithm for evaluating and managing incidentally diagnosed thyroid nodules, but several key principles apply.

The decision to continue routine follow-up of a cytologically benign, asymptomatic nodule should be based on its ultrasound characteristics rather than an increase in its volume alone. There is no complete agreement about how to surveil subcentimeter (less than 1 cm) nodules. Highly suspicious subcentimeter nodules warrant repeat ultrasound at 6 to 12 months, whereas nodules with a very low level of suspicion—regardless of size—do not require follow-up imaging at all. The American College of Radiology recommends against scanning intervals of less than 1 year, except for biopsy-proven cancers under active surveillance.

The chance of a future cancer being found in a nodule with benign cytology is low, and it essentially becomes zero if a second sampling also yields benign cytology. Current guidelines recommend repeat FNA when concerning ultrasound characteristics develop or when the nodule's volume increases by 50% or more—although this volume threshold has been shown to have low specificity for malignancy (meaning many nodules that grow are still benign).

Nodules with nondiagnostic cytology should undergo repeat biopsy about 4 to 6 weeks later. Alternatively, core needle biopsy can be considered, especially if concerning ultrasound features are present.

Nodules that fall below the biopsy threshold but have "high-risk" features represent a challenging category and are subject to debate. Most guidelines recommend monitoring such high-risk subcentimeter nodules with repeat ultrasound every 6 to 12 months, unless additional risk factors are present. In clinical practice, however, many patients prefer not to wait and insist on proceeding with FNAB. Sample adequacy is an important issue: it has been reported to be as low as 72.2% for nodules 3 to 6 mm, 84.9% for nodules 7 to 10 mm, and 63% in the presence of macrocalcifications.

TSH suppression therapy (using thyroid hormone medication to shrink nodules in people with normal thyroid function) was in vogue for many years. A meta-analysis published in 2005 found an 88% likelihood of achieving a reduction in nodule volume of greater than 50% compared with placebo or no treatment. However, the number needed to treat was 8 to 1 (meaning 8 patients needed treatment for 1 to benefit), and TSH suppression exposed patients to the risk of bone and cardiac complications from chronic, medically induced hyperthyroidism. Current American Thyroid Association guidelines recommend against TSH suppression therapy as a standard treatment for euthyroid (normal thyroid function), iodine-sufficient populations.

When Surgery Is Needed

Thyroid surgery for managing a benign nodule may be considered when there is an association with compression symptoms. These symptoms include dysphagia (difficulty swallowing), hoarseness, or a choking sensation. Surgery may also be considered for cosmetic concerns. Some researchers advocate that nodules greater than 3 to 4 cm should be considered for removal, although practical experience indicates that close follow-up of cytologically proven benign, asymptomatic nodules of this size is reasonable.

Nodules found to harbor cancer—and those with indeterminate cytology or molecular test results indicating a significant cancer risk—typically undergo resection (surgical removal). The extent of thyroid surgery is influenced by risk factors such as a history of childhood radiation exposure. It is also influenced by histology, including aggressive differentiated thyroid cancer variants and medullary or anaplastic thyroid cancer. Other factors are the presence of bilateral nodules, particularly those larger than 1 cm on the opposite side, or a family history of thyroid cancer.

Active surveillance is an option for micropapillary thyroid cancers (papillary cancers smaller than 1 cm) that appear to be limited to the thyroid. It is preferable that such microcarcinomas be surrounded by a rim of normal thyroid tissue and that close follow-up with serial ultrasound imaging occurs.

Thyroid surgery is best performed by an experienced, high-volume thyroid surgeon to minimize surgical risks. These include transient or permanent hypoparathyroidism (underactive parathyroid glands, which can cause low calcium levels), hoarseness, and voice changes from recurrent laryngeal nerve damage. Patients should be counseled that hypothyroidism (underactive thyroid) with a lifelong need for thyroid hormone therapy is a risk of thyroid surgery. It occurs in approximately 15% to 50% of patients after hemithyroidectomy (removal of half the thyroid), with higher rates in patients who have smaller amounts of residual thyroid tissue, a higher preoperative TSH level, or underlying chronic lymphocytic thyroiditis (Hashimoto's thyroiditis, an autoimmune inflammation of the thyroid)—and, of course, in all patients after total thyroidectomy.

Nonsurgical Treatment Options

Nonsurgical management of benign thyroid nodules is a growing field. It includes ethanol ablation, which injects alcohol to destroy nodule tissue. It also includes sclerotherapy for cysts, which injects a substance to collapse the cyst. It also includes thermal techniques such as radiofrequency ablation, laser ablation, microwaves, and high-intensity focused ultrasound. All of these thermal techniques use heat to shrink nodules.

Before any nonsurgical therapeutic option is used, the nodule should be proven benign—preferably by two FNAB samples, although one may suffice in very low-risk nodules. Anticoagulation therapy (blood thinners) should be held before the procedure. Complications associated with thermal treatments vary by patient selection and operator experience. Ethanol ablation appears to be a more appropriate treatment option for sclerosing pure thyroid cysts or treating autonomous nodules. Intraprocedural perithyroidal ethanol leakage (alcohol leaking outside the thyroid) can cause patient discomfort.

What This Means for Patients

If you have been told you have a thyroid nodule, the most important takeaway from this review is that the overwhelming majority are benign and can be safely monitored. Not every nodule needs a biopsy, and not every biopsy result needs surgery.

The evaluation of your nodule should be personalized. Your doctor will consider its ultrasound appearance, using a standardized risk score. Your doctor will also consider its size, your TSH level, and your personal and family history. If a biopsy is done, your doctor will also consider the cytology and possibly molecular test results.

Key points to keep in mind:

• Routine screening for thyroid nodules in people without symptoms is not recommended.
• Ultrasound is the best tool for assessing nodule structure, and modern risk-scoring systems (such as TI-RADS or ATA categories) help determine whether a biopsy is truly needed.
• Biopsy of nodules smaller than 1 cm is generally not automatic; active surveillance with repeat imaging is often preferred.
• Molecular testing can help avoid unnecessary surgery when biopsy results are indeterminate.
• Active surveillance is a legitimate option for small papillary thyroid cancers (micropapillary, less than 1 cm) with favorable features.
• For benign nodules causing symptoms or cosmetic concern, nonsurgical options such as ethanol ablation and thermal techniques are increasingly available.
• If surgery is recommended, choose a high-volume, experienced thyroid surgeon to minimize risks.

Limitations of the Evidence

This article is a narrative review, not a new clinical trial. It summarizes existing research and expert guidelines rather than generating new primary data. Several specific limitations are worth noting:

• Individual ultrasound features have broad ranges of sensitivity and specificity, meaning none is accurate alone—assessment requires combining multiple features.
• There is no unanimous consensus across professional societies on the optimal thresholds for biopsy or follow-up. Different systems (ACR TI-RADS, ATA, AACE/ACE/AME, EU-TIRADS, K-TIRADS) use different cutoffs.
• Studies on the relationship between nodule size and FNAB accuracy have yielded conflicting results.
• The use of molecular marker results to guide therapy has not been proven to improve outcomes and is not the standard of care; cost may be prohibitive.
• The significance of nodule volume growth of 50% or more has low specificity for malignancy—many growing nodules remain benign.
• Optimal surveillance for subcentimeter nodules remains debated.
• The clinical significance of incidental thyroid cancers found on PET/CT is uncertain; they appear not to affect mortality, suggesting possible overdiagnosis.
• TSH suppression therapy is no longer recommended because of bone and cardiac risks, despite its ability to shrink nodules.

Practical Recommendations

1. Do not panic. Most thyroid nodules are benign, with a malignancy rate under 5% in most series. They can usually be monitored safely.
2. Get an expert ultrasound. Thyroid ultrasound is the gold standard for assessing a nodule's appearance. Ask that your nodule be classified using a standardized risk system.
3. Have your thyroid function checked. A TSH level helps determine whether nuclear imaging (scintigraphy) is needed to look for a hyperfunctioning nodule.
4. Understand the biopsy decision. Biopsy should be tailored to risk stratification—size plus ultrasound appearance—not performed automatically. Nodules under 1 cm rarely need immediate biopsy.
5. If biopsy results are indeterminate (Bethesda III or IV), ask about molecular testing. These tests can reduce the need for diagnostic surgery.
6. Discuss surveillance versus surgery. For benign nodules and for small papillary microcarcinomas with favorable features, active surveillance is a reasonable option.
7. Know your risk factors. Childhood radiation exposure, certain genetic syndromes, and a family history of medullary thyroid cancer or MEN syndrome should prompt closer attention.
8. Explore nonsurgical options if a benign nodule is symptomatic. Ethanol ablation, sclerotherapy, and thermal techniques are emerging alternatives to surgery.
9. If surgery is needed, choose an experienced, high-volume thyroid surgeon to reduce the risk of complications such as parathyroid damage, voice changes, and postoperative hypothyroidism.

Above all, treatment options should be individualized for each patient's particular situation, and decisions should be made in partnership with your care team.

Frequently Asked Questions

I've been told I have a thyroid nodule. How likely is it to be cancer?

Most thyroid nodules are benign. The rate of malignancy in thyroid nodules is less than 5% in general, with most series citing 7% to 15% for nodules that come to medical attention. The rise in thyroid cancer diagnoses is largely explained by increased imaging picking up small, low-risk tumors that would never have caused harm.

What is a TI-RADS score and what does it mean for me?

TI-RADS is a standardized system from the American College of Radiology that uses a point-scoring method based on nodule composition, echogenicity, shape, size, margins, and echogenic foci. The recommendation for fine-needle aspiration biopsy is based on combining the TI-RADS score with the nodule's size. It helps determine whether further testing is needed.

Will I need a biopsy for my thyroid nodule?

Not every nodule needs a biopsy. Biopsy should be tailored to risk stratification—size plus ultrasound appearance—not performed automatically. Nodules under 1 cm rarely need immediate biopsy. Both the ACR TI-RADS and ATA systems recommend against automatically biopsying nodules smaller than 1 cm and instead lean toward active surveillance with repeat imaging.

What happens if my biopsy result is indeterminate?

Indeterminate cytology (Bethesda III or IV) has associated malignancy risks of 10% to 30% and 25% to 40%, respectively. Historically, these cases required surgery for diagnosis, leading to unnecessary operations. Molecular testing of the sample can identify genomic alterations and greatly reduce the need for diagnostic surgery. Ask your doctor about molecular testing.

Can I just monitor my nodule instead of having surgery?

Yes, for many nodules. Benign nodules can usually be safely monitored. For micropapillary thyroid cancers (papillary cancers smaller than 1 cm) that appear limited to the thyroid, active surveillance is a legitimate option. It is preferable that such microcarcinomas be surrounded by a rim of normal thyroid tissue and that close follow-up with serial ultrasound imaging occurs.

What are the risks of thyroid surgery?

Risks include transient or permanent hypoparathyroidism (underactive parathyroid glands, which can cause low calcium levels), hoarseness, and voice changes from recurrent laryngeal nerve damage. Hypothyroidism with a lifelong need for thyroid hormone therapy occurs in approximately 15% to 50% of patients after hemithyroidectomy, and in all patients after total thyroidectomy. An experienced, high-volume thyroid surgeon minimizes these risks.

Are there nonsurgical treatments for benign thyroid nodules?

Yes. Nonsurgical options include ethanol ablation, sclerotherapy for cysts, and thermal techniques such as radiofrequency ablation, laser ablation, microwaves, and high-intensity focused ultrasound. Before any nonsurgical option is used, the nodule should be proven benign—preferably by two FNAB samples, although one may suffice in very low-risk nodules. These are increasingly available alternatives to surgery.

I have a thyroid nodule with an indeterminate biopsy result (Bethesda III or IV) and surgery has been recommended — when should I seek a second opinion?

Indeterminate cytology carries a malignancy risk of 10% to 30% for Bethesda III and 25% to 40% for Bethesda IV, and these cases historically required surgery just to reach a diagnosis. Molecular testing of the biopsy sample can identify genomic alterations and reduce the need for diagnostic surgery. A review of your cytology and whether molecular testing was offered is a reasonable point to seek another opinion. A second review can also confirm the ultrasound risk classification and whether active surveillance is appropriate. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: Update on the Evaluation of Thyroid Nodules

Publication: Journal of Nuclear Medicine, 2021; Volume 62, Supplement 2, pages 13S–19S. DOI: 10.2967/jnumed.120.246025. Received July 6, 2020; revision accepted September 29, 2020. Copyright 2021 by the Society of Nuclear Medicine and Molecular Imaging.

Key words: oncology; fine-needle aspiration; imaging; molecular testing; risk stratification; thyroid nodules

This patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and does not replace personalized medical advice from your healthcare provider.