# Understanding Thyroid Nodules: A Complete Patient Guide to Diagnosis, Risks, and Treatment Thyroid nodules are extremely common — they can be found in up to 68% of randomly selected individuals when high-resolution ultrasound is used, yet only about 7-15% turn out to be cancerous. This comprehensive guide translates the key medical evidence about how doctors evaluate, diagnose, and treat thyroid nodules, including the lifetime risk of developing one (5-10%), the specific warning signs that raise concern for malignancy, and the modern diagnostic steps — from TSH blood tests and ultrasound to fine-needle aspiration biopsy (FNAB) — that help avoid unnecessary surgery while catching cancers early. # Understanding Thyroid Nodules: A Complete Patient Guide to Diagnosis, Risks, and Treatment ## Table of Contents - Key Points - What Is a Thyroid Nodule? Background and Key Facts - Risk Factors and Warning Signs: What Your Doctor Looks For - The Diagnostic Workup: How Thyroid Nodules Are Evaluated - Laboratory Tests: The Role of Blood Work - Imaging Studies: Ultrasound, Nuclear Scans, CT, MRI, and PET - Fine-Needle Aspiration Biopsy: The Most Important Diagnostic Step - Management and Treatment: What Happens Next? - Special Considerations: Incidental Findings and Autonomously Functioning Nodules - Guidelines for Pediatric Patients: Special Rules for Children - Limitations: What This Article Cannot Tell You - Recommendations: What Patients Should Do - Frequently Asked Questions - Source Information ## Key Points - Thyroid nodules are found in 19–68% of randomly selected people on high-resolution ultrasound, but only 7–15% are cancerous. - Warning signs for malignancy include age under 20 or over 70, male sex, hoarseness, trouble swallowing, firm or immobile nodule, and enlarged neck lymph nodes. - The key diagnostic steps are a TSH blood test, thyroid ultrasound, and fine-needle aspiration biopsy (FNAB), which has mean sensitivity over 80% and specificity over 90%. - FNAB reduces unnecessary thyroid surgery by 20–50% and increases cancer detection in surgical specimens by 15–45%. - Benign nodules are usually monitored with ultrasound every 6–18 months; surgery is considered for follicular neoplasm, suspicious, or malignant biopsy results. ## What Is a Thyroid Nodule? Background and Key Facts Nodular disease of the thyroid gland is remarkably prevalent in the United States. The lifetime risk for developing a palpable (felt on physical exam) thyroid nodule is estimated to be **5-10%**. However, the true number is far higher: high-resolution ultrasound has revealed thyroid nodules in **19-68% of randomly selected individuals**. The condition affects more women than men, a pattern that has been recognized for decades. So what exactly is a thyroid nodule? It is an abnormal growth or lump that forms within the thyroid gland, a butterfly-shaped organ located in the front of the neck that produces hormones regulating metabolism. Most nodules cause no symptoms at all. They may be discovered during a routine physical examination, or they may show up incidentally when imaging is performed for other reasons. Here is the most reassuring number to remember: while nodular disease of the thyroid is very common, malignancy (cancer) of the thyroid occurs in only **7-15% of nodules**. That means roughly 85-93 out of every 100 nodules are benign (non-cancerous). A 12-year-old patient might have an asymptomatic (symptom-free) palpable nodule noticed on a routine physical exam. In such cases, surgical specimens have shown papillary carcinoma, the most common type of thyroid cancer. Another example involves a large goiter where the right lobe revealed a solid nodule with necrotic and hemorrhagic areas — the histologic diagnosis was follicular thyroid carcinoma. These cases illustrate why evaluation matters, even when a nodule causes no symptoms. The incidence of both thyroid nodules and thyroid malignancy has increased rapidly in recent years. The most recent data for the US indicates approximately **63,000 new thyroid cancer cases per year**. This increase is thought to be largely related to early detection by high-resolution ultrasound and the discovery of sub-clinical (not yet felt or causing symptoms) thyroid nodules. Evidence supporting this explanation comes from the observation that survival rates for thyroid cancer have remained fairly stable during the same period. In other words, we are not necessarily seeing more cancer — we are simply finding it earlier and more often. While roughly 7-15% of thyroid nodules are malignant, the remainder represent a variety of benign diagnoses. These include **colloid nodules** (clusters of thyroid cells and gel-like material), **degenerative cysts**, **hyperplasia** (overgrowth of normal cells), **thyroiditis** (inflammation of the thyroid), and **benign neoplasms** (non-cancerous tumors). A rational approach to management is based on the clinician's ability to distinguish the more common benign diagnoses from malignancy in a highly reliable and cost-effective manner. ## Risk Factors and Warning Signs: What Your Doctor Looks For A comprehensive history and physical examination provides the foundation for decision-making in the management of thyroid nodules. Several features in a patient's history and physical exam significantly influence the statistical probability that a nodule is malignant. These factors do not provide absolute diagnostic information — they are guidelines to help doctors weigh the odds and decide which tests are needed. **Factors suggesting a malignant (cancerous) diagnosis include the following:** - Age younger than 20 years or older than 70 years - Male sex - Associated symptoms of dysphagia (difficulty swallowing) or dysphonia (hoarseness or voice changes) - History of neck irradiation (radiation exposure to the neck area) - Prior history of thyroid carcinoma - Firm, hard, or immobile nodule (a nodule that does not move when you swallow) - Presence of cervical lymphadenopathy (swollen or enlarged lymph nodes in the neck) **Factors suggesting a benign (non-cancerous) diagnosis include the following:** - Family history of autoimmune disease (e.g., Hashimoto thyroiditis) - Family history of benign thyroid nodule or goiter - Presence of thyroid hormonal dysfunction (e.g., hypothyroidism or hyperthyroidism) - Pain or tenderness associated with the nodule - Soft, smooth, and mobile nodule A historical axiom in medicine was that a multinodular goiter (an enlarged thyroid with multiple nodules) without a dominant nodule, or a solitary cyst, suggested a benign diagnosis. However, contemporary studies — including those incorporating image-guided fine-needle aspiration biopsy — have raised questions about this assumption. The size of a solid thyroid nodule on ultrasound may also carry diagnostic importance, because **nodules larger than 3 cm are thought to have an increased risk of malignancy**. Interestingly, nonpalpable nodules (unable to be felt on exam) that are found incidentally on high-resolution ultrasound may carry a risk of malignancy comparable to that of palpable nodules. This means that just because a nodule cannot be felt does not mean it can be ignored. ## The Diagnostic Workup: How Thyroid Nodules Are Evaluated The evaluation of a solitary thyroid nodule involves a stepwise approach. The most important routine aspects include a thorough history and physical examination, measurement of the serum thyroid-stimulating hormone (TSH) level, ultrasound imaging, and fine-needle aspiration biopsy (FNAB) of the nodule. Subsequent management depends largely on the diagnosis obtained from FNAB. ## Laboratory Tests: The Role of Blood Work The most important laboratory test is a **sensitive thyroid-stimulating hormone (TSH) assay**, which is used to screen for hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). In addition, obtaining serum thyroxine (T4) and triiodothyronine (T3) levels may be helpful, particularly when TSH levels are low-normal or high-normal. In most cases of solitary thyroid nodules, the TSH level is normal. When the TSH is normal, no additional laboratory studies may be required in the diagnostic evaluation unless autoimmune disease such as Hashimoto thyroiditis is suspected. When the patient's history and physical findings reveal a family history of, or clinical suspicion for, Hashimoto thyroiditis, doctors should obtain serum **antithyroid peroxidase (anti-TPO) antibody** and **antithyroglobulin (anti-Tg) antibody** levels. It is important to note that a diagnosis of Hashimoto thyroiditis does not exclude the possibility of malignancy — the two conditions can coexist. Additional laboratory studies are unnecessary in the routine initial diagnostic evaluation of a solitary thyroid nodule. ## Imaging Studies: Ultrasound, Nuclear Scans, CT, MRI, and PET ### Thyroid Scintigraphy (Nuclear Imaging) In most medical centers, the routine initial diagnostic evaluation of a solitary thyroid nodule no longer includes nuclear imaging studies. In the past, radionuclide scanning was performed routinely. This technique uses a radioactive isotope to describe a nodule as **hot**, **warm**, or **cold**, based on its relative uptake of the isotope. Hot nodules indicate autonomously functioning nodules (they produce thyroid hormone on their own), warm nodules suggest normal thyroid function, and cold nodules indicate hypofunctional or nonfunctional thyroid tissue. The key takeaway: **hot nodules are rarely malignant**; however, **5-8% of warm or cold nodules are malignant**. This is why a cold nodule warrants further investigation. ### Ultrasonography Because of advances in technology, ultrasonography is highly sensitive in determining the size and number of thyroid nodules. However, by itself, ultrasound cannot reliably distinguish a benign nodule from a malignant nodule. Combining high-resolution sonography with Doppler and spectral analysis of the vascular (blood vessel) characteristics of a nodule holds promise as a screening tool. Studies have shown that the risk of malignancy is lower in nodules with a predominantly **perinodular** vascular pattern (blood vessels around the edge) than in nodules with an exclusively **central** vascular pattern (blood vessels in the middle). Furthermore, combining vascular characteristics with other ultrasound parameters — including the presence of a halo (a rim around the nodule), **microcalcifications** (tiny calcium deposits), cross-sectional diameter, and echogenicity (how the nodule reflects ultrasound waves) — can increase the predictive value of imaging. Efforts to standardize thyroid ultrasound reporting have been made in recent years. Su H and colleagues published a consensus report by a multidisciplinary panel of specialists outlining recommendations for standardized thyroid ultrasound reporting, including characterization of both thyroid nodules and regional lymph nodes in the neck. Haugen and colleagues developed the **2015 American Thyroid Association (ATA) guidelines** for management of thyroid nodules, which stratified the estimated risk of malignancy based on specific ultrasound characteristics and provided recommendations for which nodules warrant biopsy based on suspicious ultrasound patterns and nodule size. Tessler and colleagues expanded on these guidelines, proposing a risk-stratification system based on ultrasound characteristics — **composition, echogenicity, shape, margin, and echogenic foci** — to determine which nodules need biopsy. Ultrasound is also valuable as a guide for FNAB. Data suggest that ultrasonography-guided FNAB may be preferable to palpation-guided (feeling the nodule) FNAB. While sensitivity and specificity are not clearly and significantly different between the two approaches, many authors consider image-guided FNAB to hold certain advantages. For example, ultrasound guidance is particularly helpful for assessing nonpalpable or small nodules, nodules with cystic components, or nodules that are difficult to access (such as posterior or substernal nodules located behind the breastbone). Ultrasonography-guided FNAB combined with **on-site cytologic verification** (a cytotechnologist or pathologist checks the specimen immediately to confirm it contains enough cells) may provide the highest sensitivity and specificity. Whether this is the most cost-effective approach for all thyroid nodules remains an open question. One study by Mazzaglia evaluated 261 patients undergoing surgical evaluation for thyroid disease. The investigator investigated whether office-based, surgeon-performed ultrasonographic examination significantly affected operative treatment, even though all patients had previously undergone outside ultrasound examinations. The results were striking: treatment plans for **46 patients (17.6%) were altered** because of significant differences between outside and surgeon-administered ultrasounds. In 12 patients, previously unidentified nonpalpable enlarged lymph nodes were found, and biopsy revealed metastatic thyroid cancer in **3 of those patients**. Mazzaglia concluded that surgeon-performed ultrasound can lead to necessary changes in surgical treatment and help avoid unnecessary surgery. ### CT, MRI, and PET Scanning CT scanning or MRI is generally not cost-effective in the initial evaluation of solitary thyroid nodules. These studies may be useful in assessing thyroid masses that are largely substernal (extending behind the breastbone). In some cases, CT scan-guided FNAB may be helpful. PET scanning with 18F-fluorodeoxyglucose (a radioactive sugar molecule) is at present primarily an investigational tool, though it may have a future role in evaluating metastatic disease. However, a study by Deandreis and colleagues found that PET scanning offered **no additional diagnostic benefit** in the evaluation of a thyroid nodule with indeterminate cytopathology on FNAB. In the past, nuclear imaging of the thyroid (often combined with ultrasound) was routinely performed in the initial assessment of nodules. But because only 10% of solitary thyroid nodules are hot, and because 90% of cold nodules are not malignant, nuclear imaging typically offers a low yield of cancer diagnoses in surgical specimens when used as the main guide for referral to a surgeon. ## Fine-Needle Aspiration Biopsy: The Most Important Diagnostic Step FNAB has emerged as **the most important step** in the diagnostic evaluation of thyroid nodules. Numerous studies have established FNAB as highly accurate, with a **mean sensitivity higher than 80%** (meaning it correctly identifies cancer in more than 8 out of 10 cancerous nodules) and a **mean specificity higher than 90%** (meaning it correctly identifies benign nodules in more than 9 out of 10 benign cases). The accuracy of FNAB depends heavily on the cytopathologist's expertise and experience, as well as the technical skill of the physician performing the biopsy. FNAB is also **highly cost-effective** compared with traditional workups that relied heavily on nuclear imaging and ultrasound. Routine use of FNAB in evaluating thyroid nodules can reduce the need for diagnostic thyroidectomy (surgical removal of the thyroid) by **20-50%** while increasing the yield of cancer diagnoses in thyroid specimens by **15-45%**. In simple terms, FNAB helps more patients avoid unnecessary surgery and helps surgeons focus their efforts on nodules that truly are cancerous. ### The Bethesda System: Standardized Reporting When FNAB provides adequate cellular material, the specimen can be assigned to one of several diagnostic classifications. To improve communication and clarity, the National Cancer Institute convened a conference in 2007 that developed a consensus terminology known as the **Bethesda System for Reporting Thyroid Cytopathology**. The recommended diagnostic categories are: benign, atypia of undetermined significance, follicular neoplasm, suspicious for malignancy, malignancy, and nondiagnostic. **The respective risk of malignancy associated with each diagnostic category is as follows:** - **Benign** — less than 1% risk of cancer - **Atypia of undetermined significance (AUS)** — 5-10% risk - **Follicular neoplasm** — 20-30% risk - **Suspicious for malignancy** — 50-75% risk - **Malignant** — 100% risk (by definition) The main weakness of FNAB involves **hypocellular aspirates** (specimens containing too few cells) and aspirates with high follicular cellularity (many follicular cells). Hypocellular aspirates may be observed in cystic nodules or may be related to biopsy technique. The addition of ultrasound to guide FNAB sometimes reduces technical errors. Furthermore, ultrasound guidance combined with on-site verification of specimen adequacy by a cytotechnologist or pathologist is likely to reduce the rate of nondiagnostic specimens. Aspirates characterized by high follicular cellularity suggest follicular neoplasm. However, FNAB cannot reliably distinguish a benign follicular neoplasm from a malignant one — this distinction requires surgical pathology. Similarly, aspirates that are highly cellular with Hürthle cells can be observed with benign or malignant Hürthle-cell neoplasms, and also with some cases of Hashimoto thyroiditis. ### Molecular Testing and Advances in Cytology Advances in cytologic analysis may increase the predictive value of FNAB. The incorporation of immunocytochemical studies, as well as genetic and molecular profiling of aspirates, may improve the accuracy of minimally invasive diagnostic techniques. In the specific case of aspirates revealing cytology of indeterminate significance or follicular lesions, molecular testing such as the **Afirma gene expression classifier** can aid in decision-making regarding recommendations for surgery. In those cytopathologic classifications where the risk of malignancy is relatively indeterminate (AUS, follicular neoplasm), improvement in risk assessment might be achieved by viewing the cytopathologic results in the context of ultrasonographic characteristics suspicious for malignancy. ### FNAB vs. FNNAB: A Comparative Study An Italian study compared the effectiveness of FNAB with that of **fine-needle nonaspiration biopsy (FNNAB)**, also called the "capillary technique," in evaluating thyroid nodules. The two techniques were performed on the same **104 patients** who were known to have a uninodular (single nodule) or multinodular goiter. Notably, no statistically significant difference was found between the adequacy of samples obtained through FNAB and those collected through FNNAB in diagnosing colloid, follicular, or malignant nodules. The only significant difference was in the percentage of samples yielding inadequate results: **16.3% for FNAB and 5.8% for FNNAB**. The authors suggested that the frequency of inadequate samples was lower for FNNAB because the technique allows better-quality specimens to be collected. Otherwise, both techniques were found to be useful and cost-effective. ### Experience Matters Ultrasonography-guided FNAB has become increasingly common, but clinicians need adequate sampling during biopsies to provide an accurate diagnosis and to avoid repeating the procedure. Insufficient experience with the technique is an important factor in the yield of this procedure. One study found, not surprisingly, that physicians with more experience in performing ultrasound-guided FNAB have **lower rates of inadequate samples**. Although the inexperienced group had smaller size nodules, this likely did not affect the results given the obvious difference in competency rates. ## Management and Treatment: What Happens Next? Beyond clarifying terminology, the Bethesda conference also established a consensus for the indications to perform FNAB of thyroid nodules, as well as post-FNAB management options. The current state of the art is nicely outlined in a review by Layfield and colleagues. Using the Bethesda system, the **follicular neoplasm**, **suspicious for malignancy**, and **malignant** classifications each warrant surgical consultation. Patients with follicular cytopathology on FNAB should be referred to a surgeon because **20-30% of such nodules are malignant**. Exceptions may be made in cases of malignant lymphoma (typically not managed surgically) and anaplastic carcinoma (where surgical intervention may be futile). **For the atypia of undetermined significance (AUS) category, management options include the following:** 1. Repeat FNAB in 3-6 months; if the repeat ultrasound-guided biopsy is again atypical, surgical consultation is warranted. 1. Surgical consultation if, in addition to atypia, worrisome characteristics on ultrasound are also noted — such as hypoechogenicity (appearing darker on ultrasound), irregular borders, calcifications, or hypervascularity (increased blood flow). **Nodules classified as benign** can be safely followed with ultrasound at **6-18 month intervals**, with further intervention based on imaging features such as increased growth. Most nodules associated with benign cytopathology can be managed without routine surgical referral, provided adequate follow-up is possible. Although the incidence of false-negative results with FNAB is low, some physicians recommend repeat FNAB for confirmation **6-12 months after an initial diagnosis of a benign lesion**, or if the characteristics of the nodule change on follow-up examination. When a benign diagnosis is confirmed, referral to a surgeon is reasonable for patients with symptoms (such as dysphagia or discomfort) or concerns about cosmesis (appearance). **When findings from the aspirate are nondiagnostic**, repeat the aspiration, possibly with ultrasound guidance. Nodules for which aspirates are repeatedly nondiagnostic may ultimately require surgical management. ## Special Considerations: Incidental Findings and Autonomously Functioning Nodules ### Incidentally Discovered Thyroid Nodules (Incidentalomas) Advances in imaging technology have increased the potential for the incidental discovery of nonpalpable thyroid nodules — findings on CT, MRI, or ultrasound performed for unrelated reasons. When the history and physical findings result in a low index of suspicion for malignancy, periodic follow-up evaluation with high-resolution ultrasound is appropriate. Specific guidelines for these nodules have not been established, but findings have raised concern that the incidence of malignancy in nonpalpable nodules may approach that of palpable nodules. For this reason, if sequential sonograms (for example, obtained at 6-month intervals) reveal an increase in nodular size, ultrasound-guided FNAB may be appropriate — **even if the nodule remains nonpalpable**. ### Autonomously Functioning Thyroid Nodules Patients with solitary thyroid nodules associated with suppressed TSH levels (indicating the nodule is producing thyroid hormone on its own), with overt or subclinical hyperthyroidism, do not require routine FNAB. In such cases, the patient may be referred to an endocrinologist to discuss **iodine-131 treatment versus surgical intervention**. ## Guidelines for Pediatric Patients: Special Rules for Children Clinical practice guidelines on the management of pediatric thyroid nodules and differentiated thyroid carcinoma (DTC) were published in **2022** by the European Thyroid Association. These guidelines address several key areas: - **Ultrasonography of the neck** is recommended to evaluate thyroid nodules. For pediatric patients with nodules suspected of being malignant, fine-needle biopsy is recommended. - For the **preoperative evaluation** of a pediatric patient with DTC, neck palpation, comprehensive neck ultrasonography, and laboratory workup are recommended. Additional genetic testing or imaging studies are suggested for patients with familial or extensive disease. - **Total thyroidectomy** (removal of the entire thyroid gland) is the suggested treatment for children with DTC. - For patients with incidentally found, very small thyroid carcinoma and nonaggressive histologic features, **hemithyroidectomy** (removal of one lobe of the thyroid) may be an option. - **Prophylactic central lymph node dissection** (removal of lymph nodes as a preventive measure) should be reserved for patients with advanced thyroid cancer — specifically those with extracapsular extension (spread beyond the capsule of the gland), vascular invasion, or distant metastases. - **Radioactive iodine (I-131) therapy** is suggested for all children following total thyroidectomy. - Serum **thyroglobulin measurement and neck ultrasonography** are recommended for follow-up after treatment for DTC during childhood. Monitoring of thyroid-stimulating hormone levels and suppression to low-normal values are also suggested. - For children with persistent or recurrent cervical disease, surgery or I-131 therapy is suggested, depending on the size, tumor load, and degree of progression. - **I-131 therapy is recommended as the first-line treatment** for patients with pulmonary metastases. - Postoperative monitoring of **laryngeal nerve and parathyroid gland function** is recommended. - Continued follow-up is suggested for **at least 10 years after surgery**. ## Limitations: What This Article Cannot Tell You It is important to understand the limitations of this information. This article is based on a comprehensive medical review article published on Medscape, and it reflects the state of knowledge as of its last update in December 2022. Medical knowledge evolves rapidly, and new guidelines or treatment options may have emerged since that time. The statistics in this article are population-level estimates derived from various studies. They describe what happens on average across large groups of patients, but they cannot predict what will happen in any individual case. Your personal risk of malignancy depends on a unique combination of your age, sex, medical history, family history, ultrasound findings, and biopsy results. Additionally, some of the studies cited in this article (such as the Italian comparison of FNAB versus FNNAB, and the Mazzaglia study of surgeon-performed ultrasound) involved relatively small patient populations. Findings from single-institution studies may not always be reproducible in other settings. Finally, the field of molecular testing for thyroid nodules is advancing rapidly, and the specific tests mentioned (such as the Afirma gene expression classifier) are continually being refined and validated. ## Recommendations: What Patients Should Do If you have been told you have a thyroid nodule — or if a nodule was found incidentally on an imaging study — here is a practical summary of what the evidence suggests: 1. **Do not panic.** Remember that only 7-15% of thyroid nodules are malignant. The vast majority are benign colloid nodules, cysts, or benign growths. 1. **Get a thorough clinical evaluation.** This should include a careful history and physical examination, with attention to the warning signs listed in this article (firm nodules, voice changes, difficulty swallowing, enlarged lymph nodes, age extremes, male sex, prior neck radiation, prior thyroid cancer). 1. **Have a TSH blood test.** This is the single most important laboratory test. If your TSH is low, you may have an autonomously functioning "hot" nodule, which is very unlikely to be cancer and may not require biopsy at all. 1. **Get a high-quality thyroid ultrasound.** This is the best imaging tool for determining nodule size, composition, and suspicious features such as microcalcifications, irregular borders, and central vascularity. Be aware that the experience of the person reading the ultrasound matters. 1. **Understand the Bethesda category if you have a biopsy.** If your FNAB results are reported using the Bethesda System, ask your doctor what your category means in terms of cancer risk — benign (<1%), atypia of undetermined significance (5-10%), follicular neoplasm (20-30%), suspicious for malignancy (50-75%), or malignant (100%). 1. **Follow the recommended follow-up schedule.** Benign nodules are typically monitored with ultrasound every 6-18 months. If a nodule grows, a repeat biopsy may be needed. 1. **Consider a second opinion for indeterminate results.** If your biopsy shows atypia of undetermined significance or follicular neoplasm, discuss options with your doctor — including repeat biopsy in 3-6 months, molecular testing, or surgical consultation. The right choice depends on your specific situation and preferences. 1. **If surgery is recommended, choose an experienced thyroid surgeon.** Remember that surgeon-performed ultrasound can change surgical plans in nearly 18% of cases, sometimes finding lymph node metastases that were previously missed. 1. **If you have a family history of autoimmune thyroid disease or thyroid nodules, tell your doctor.** These factors suggest a benign diagnosis, but they do not rule out cancer entirely. Ultimately, the most important message is this: thyroid nodules are common, most are harmless, and modern medicine has a very reliable, stepwise approach to sorting out which ones need treatment. With proper evaluation, the vast majority of patients can avoid unnecessary surgery while still catching the cancers that do occur. ## Frequently Asked Questions ### How common are thyroid nodules, and how often are they cancer? Thyroid nodules are very common. High-resolution ultrasound finds them in 19–68% of randomly selected people, and the lifetime risk of a palpable nodule is 5–10%. However, only about 7–15% of nodules are cancerous. That means roughly 85–93 out of every 100 nodules are benign, so most people with a nodule do not have cancer. ### What warning signs make a thyroid nodule more concerning for cancer? Features that raise concern include age under 20 or over 70, male sex, difficulty swallowing or hoarseness, a history of neck radiation or thyroid cancer, a firm or immobile nodule, and enlarged neck lymph nodes. These factors do not diagnose cancer but help doctors decide which tests are needed. A soft, mobile, tender nodule is more often benign. ### What tests will I need for a thyroid nodule? The usual workup includes a history and physical exam, a TSH blood test, a thyroid ultrasound, and often a fine-needle aspiration biopsy (FNAB). TSH screens for under- or overactive thyroid. Ultrasound shows the nodule's size and features. FNAB, the most important diagnostic step, samples cells to check for cancer. Additional tests may be ordered based on results. ### What does a fine-needle aspiration biopsy (FNAB) involve, and how accurate is it? FNAB uses a thin needle to take cells from the nodule, usually guided by ultrasound. Studies show it has a mean sensitivity above 80% and specificity above 90%. Accuracy depends on the cytopathologist's expertise and the physician's skill. FNAB can reduce unnecessary thyroid surgery by 20–50% while increasing cancer detection in surgical specimens by 15–45%. ### What do the Bethesda System categories mean for my cancer risk? The Bethesda System classifies biopsy results with estimated cancer risks: benign (less than 1%), atypia of undetermined significance (5–10%), follicular neoplasm (20–30%), suspicious for malignancy (50–75%), and malignant (100% by definition). Your doctor uses your category to recommend follow-up, repeat biopsy, molecular testing, or surgery. Ask what your specific category means for you. ### If my biopsy is benign, what follow-up do I need? Benign nodules are typically monitored with ultrasound every 6–18 months. Further action depends on imaging features such as increased growth. Most benign nodules do not need surgery if adequate follow-up is possible. Some doctors recommend a repeat biopsy 6–12 months after a benign result, or sooner if the nodule's characteristics change. ### When is surgery recommended for a thyroid nodule? Surgery is generally advised for biopsy results of follicular neoplasm, suspicious for malignancy, or malignant. Follicular neoplasm carries a 20–30% cancer risk, so surgical consultation is recommended. For atypia of undetermined significance, options include repeat biopsy in 3–6 months or surgery if ultrasound shows worrisome features. Benign nodules usually do not require surgery unless symptoms or cosmetic concerns exist. ### When should a patient with an indeterminate thyroid nodule biopsy result seek a second opinion? A biopsy reported as atypia of undetermined significance carries a 5-10% cancer risk, and follicular neoplasm carries a 20-30% risk. For these indeterminate categories, options include repeat biopsy in 3-6 months, molecular testing, or surgical consultation, and the choice depends on the individual situation. Because follicular neoplasm cannot be reliably separated from benign disease by biopsy alone, and ultrasound features such as hypoechogenicity, irregular borders, calcifications, or hypervascularity add information, an independent review of the cytology and imaging can help clarify whether surgery is warranted. Diagnostic Detectives Network provides independent expert second opinions. ## Source Information This patient-friendly article is based on peer-reviewed research published on Medscape. The original article details are below for reference. **Original Article Title:** Author: Steven K Dankle, MD; Chief Editor: George T Griffing, MD more... **Original Author:** Steven K Dankle, MD **Chief Editor:** George T Griffing, MD **Last Updated:** December 14, 2022 **Original Publication Source:** Medscape — eMedicine (https://emedicine.medscape.com/article/127491-overview) *Disclaimer: This patient-friendly summary is provided for educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional regarding your specific medical condition. This content is based on the state of medical knowledge as of the original article's last update in December 2022.* --- Publisher: Diagnostic Detectives Network (https://diagnosticdetectives.com) — independent multi-expert medical second opinions, worldwide, private-pay. Author byline: Anton Titov, MD, PhD. Contact: https://diagnosticdetectives.com/pages/contact Canonical page: https://diagnosticdetectives.com/products/understanding-thyroid-nodules-a-complete-patient-guide-to-diagnosis-risks-and-treatment