How should a benign hyperplastic thyroid nodule classified as TIRADS (Thyroid Imaging Reporting and Data System) 2 be managed in a patient without high‑risk clinical features?

Management of TIRADS 2 Benign Hyperplastic Thyroid Nodules

A TIRADS 2 thyroid nodule requires no fine-needle aspiration and should be managed with surveillance ultrasound alone, because the malignancy risk is essentially zero (0%) and intervention offers no benefit to morbidity, mortality, or quality of life. 1, 2

Understanding TIRADS 2 Classification

• TIRADS 2 nodules are classified as benign with a 0% malignancy risk, representing lesions such as spongiform nodules, pure cysts, or nodules with comet-tail artifacts that are pathognomonic for benign disease. 2, 3

• The American College of Radiology TIRADS system specifically designates TIRADS 2 nodules as requiring no FNA regardless of size, because the ultrasound features alone exclude malignancy with near-absolute certainty. 2

• Benign hyperplastic nodules (adenomatoid nodules, colloid nodules) fall into Bethesda Category II when biopsied, carrying only a 1–3% malignancy risk—but TIRADS 2 nodules should never reach the point of biopsy because imaging alone is diagnostic. 1

Recommended Management Algorithm

Initial Assessment

• Measure serum TSH to determine thyroid functional status; if TSH is suppressed, consider thyroid scintigraphy to identify autonomous function, which further confirms benignity. 2, 4

• Perform comprehensive neck ultrasound to document nodule size, composition, echogenicity, margins, and vascularity, and to assess cervical lymph nodes for any suspicious features. 1, 2

Surveillance Protocol

• Repeat ultrasound at 12–24 months to confirm stability; TIRADS 2 nodules that remain unchanged can be followed at progressively longer intervals (every 2–3 years) or discharged from surveillance entirely. 1, 2

• Do not perform FNA even if the nodule grows, unless ultrasound features evolve to show suspicious characteristics (microcalcifications, marked hypoechogenicity, irregular margins, loss of halo) that would reclassify the nodule to a higher TIRADS category. 1, 2

Indications for Intervention

• Consider surgery only if compressive symptoms develop—dysphagia, dyspnea, voice changes, or cosmetic concerns—that are clearly attributable to the nodule and significantly impair quality of life. 1

• Thermal ablation (radiofrequency or microwave) may be offered for symptomatic benign nodules as a non-surgical alternative in appropriately selected patients. 1

Critical Pitfalls to Avoid

• Do not order radionuclide scans in euthyroid patients with TIRADS 2 nodules; scintigraphy does not add value for malignancy risk assessment when ultrasound features are definitively benign. 1, 2

• Do not employ CT or MRI for routine follow-up, because ultrasound provides superior resolution for nodule characterization and avoids unnecessary radiation exposure or cost. 1

• Do not perform FNA based on size alone; even large TIRADS 2 nodules (>4 cm) do not require biopsy if ultrasound features remain benign, though surgical consultation may be warranted for compressive symptoms. 1, 2

• Avoid overdiagnosis by adhering strictly to TIRADS criteria; the negative predictive value of TIRADS 2 is 92–100%, meaning biopsy leads to unnecessary procedures without improving outcomes. 1, 5

Special Considerations

• High-risk clinical factors (history of head/neck irradiation, family history of thyroid cancer, suspicious cervical lymphadenopathy, age <15 years) do not override TIRADS 2 classification, because the ultrasound features themselves exclude malignancy. 1, 2

• If the nodule develops new suspicious features during surveillance (e.g., microcalcifications, irregular borders, marked hypoechogenicity), reclassify it to the appropriate higher TIRADS category and proceed with FNA according to size thresholds. 1, 2

• Measure serum calcitonin only if atypical sonographic features arise during follow-up, because calcitonin testing offers higher sensitivity for detecting medullary thyroid carcinoma than repeat FNA alone. 1

Evidence Quality and Interobserver Agreement

• The interobserver agreement for TIRADS is only fair (Cohen's kappa = 0.27) across categories 2–5, but TIRADS 2 nodules with pathognomonic benign features (spongiform, pure cystic) show higher reproducibility. 5

• The negative predictive value of TIRADS 2 is 92–100% for excluding malignancy, making it one of the most reliable categories in the system. 5, 3

• Integration of thyroid scintigraphy into TIRADS evaluation is essential in iodine-deficient regions to prevent false-positive classifications; hyperfunctioning nodules have a very high negative predictive value for malignancy but may be misclassified as TIRADS 4 or 5 based on ultrasound alone. 4