What is the management approach for a TIRADS (Thyroid Imaging Reporting and Data System) 3 thyroid nodule in an adult patient with no significant past medical history?

Management of TIRADS 3 Thyroid Nodules

For TIRADS 3 thyroid nodules, surveillance with ultrasound is the standard approach rather than immediate fine-needle aspiration biopsy, with FNA reserved only for nodules ≥1.5 cm or when high-risk clinical features are present. 1

Risk Stratification and Malignancy Risk

TIRADS 3 nodules carry a low risk of malignancy (<5%), which does not justify routine biopsy for most cases. 2 The classification system stratifies nodules based on ultrasound features, with TIRADS 3 representing mildly suspicious characteristics that warrant monitoring rather than immediate tissue diagnosis. 1

Size-Based Management Algorithm

Nodules <1.5 cm

• Surveillance is recommended without immediate FNA for standard TIRADS 3 nodules below the size threshold 1, 3
• Initial follow-up ultrasound at 12-24 months to assess for interval growth or development of suspicious features 1
• Continue surveillance if stable, with repeat imaging at progressively longer intervals 1

Nodules ≥1.5 cm

• Consider FNA when nodules reach or exceed 1.5 cm, as larger size increases both malignancy risk and false-negative rates 1, 4
• Ultrasound-guided FNA is the preferred diagnostic method when biopsy is indicated 1, 5

High-Risk Clinical Features That Lower the FNA Threshold

Even for nodules <1.5 cm, FNA should be performed when any of the following high-risk features are present:

• History of head and neck irradiation (increases malignancy risk approximately 7-fold) 1
• Family history of thyroid cancer, particularly medullary carcinoma or familial syndromes 1
• Suspicious cervical lymphadenopathy on ultrasound examination 1
• Age <15 years or male gender (higher baseline malignancy probability) 1
• Rapidly growing nodule suggesting aggressive biology 1
• Firm, fixed nodule on palpation indicating potential extrathyroidal extension 1
• Vocal cord paralysis or compressive symptoms suggesting invasive disease 1
• Subcapsular location of the nodule 3

Ultrasound Features to Monitor During Surveillance

During follow-up imaging, assess for development of higher-risk features that would upgrade the nodule classification:

• Microcalcifications (highly specific for papillary thyroid carcinoma) 1
• Marked hypoechogenicity (darker than surrounding thyroid tissue) 1
• Irregular or microlobulated margins (infiltrative borders) 1
• Absence of peripheral halo (loss of thin hypoechoic rim) 1
• Central hypervascularity (chaotic internal vascular pattern) 1
• Significant interval growth (>20% increase in two dimensions) 1

Critical Pitfalls to Avoid

Do not perform FNA on TIRADS 3 nodules <1.5 cm without high-risk features, as this leads to overdiagnosis and overtreatment of clinically insignificant papillary microcarcinomas. 1, 3 The detection of small, indolent cancers does not improve mortality or quality of life outcomes. 1

Do not rely on thyroid function tests (TSH, T3, T4) for malignancy assessment, as most thyroid cancers present with normal thyroid function. 1 However, measuring TSH is appropriate to identify autonomously functioning nodules, which have extremely low malignancy risk. 6

Do not use radionuclide scanning in euthyroid patients to determine malignancy risk, as ultrasound features are far more predictive. 1 Thyroid scintigraphy is only useful when TSH is suppressed to identify hyperfunctioning nodules, which can be safely observed. 6

When Multiple Nodules Are Present

Prioritize the largest nodule for evaluation when multiple nodules are present, as larger nodules carry higher malignancy risk and contain sufficient tissue for adequate cytological evaluation. 1 If the largest nodule is TIRADS 3 and <1.5 cm, surveillance of all nodules is appropriate unless smaller nodules have higher TIRADS classifications or high-risk features. 1

Management Based on FNA Results (When Performed)

If FNA is performed based on size or high-risk features:

• Bethesda II (Benign): Continue surveillance with ultrasound at 12-24 months; malignancy risk is only 1-3% 1
• Bethesda III (AUS/FLUS) or IV (Follicular Neoplasm): Consider molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) or repeat FNA to refine malignancy risk 1
• Bethesda V (Suspicious) or VI (Malignant): Immediate referral to endocrine surgeon for total or near-total thyroidectomy 1
• Nondiagnostic/Inadequate: Repeat ultrasound-guided FNA; if persistently nondiagnostic, consider core needle biopsy 1

Special Consideration for Nodules ≥4 cm

Any nodule ≥4 cm warrants FNA regardless of TIRADS classification, as large size alone increases malignancy risk and false-negative rates substantially. 4 If FNA remains nondiagnostic after repeat attempts, diagnostic lobectomy should be strongly considered rather than continued surveillance. 4