Management of Thyroid Nodules

Initial Evaluation and Imaging

High-resolution ultrasound is the only appropriate first-line imaging modality for characterizing thyroid nodules, as it provides superior visualization compared to CT or MRI and can identify features that stratify malignancy risk, according to the American College of Radiology 2
Ultrasound should assess specific features including echogenicity, presence of microcalcifications, margin characteristics, presence or absence of peripheral halo, solid versus cystic composition, and vascularity pattern, as recommended by the American Institute of Ultrasound in Medicine 2
The ultrasound findings will be classified using a TIRADS category, which directly determines whether fine-needle aspiration (FNA) is indicated, based on guidelines from the American College of Radiology 3, 2

For any nodule >1 cm, FNA should be performed if there are ≥2 suspicious ultrasound features, regardless of thyroid function status, as recommended by the American Thyroid Association 1, 2
Any nodule >1 cm with suspicious ultrasound features such as hypoechogenicity, microcalcifications, irregular borders, solid composition, or abnormal blood flow should undergo FNA, according to the Society of Radiologists in Ultrasound 1, 2
TI-RADS 4 classification at 1.3 cm warrants immediate FNA, as this represents intermediate-to-high suspicion where tissue diagnosis is required, based on guidelines from the American College of Radiology 2

History of head and neck irradiation significantly increases malignancy risk, as noted by the National Comprehensive Cancer Network 2
Family history of thyroid cancer, particularly medullary thyroid carcinoma or familial syndromes, is a high-risk feature, according to the American Thyroid Association 2
Presence of suspicious cervical lymphadenopathy on examination or imaging is a concerning feature, as recommended by the Society of Nuclear Medicine and Molecular Imaging 2

Consider serum calcitonin measurement as part of the diagnostic workup to screen for medullary thyroid cancer, which has higher sensitivity than FNA alone for this specific cancer type, based on guidelines from the Endocrine Society 1, 2

Results will be reported using the Bethesda Classification System, which stratifies malignancy risk and determines whether observation, repeat biopsy, molecular testing, or surgery is indicated, as recommended by the National Cancer Institute 2
If FNA yields inadequate samples, repeat FNA under ultrasound guidance is recommended, according to the American Thyroid Association 1, 2
For indeterminate results, molecular testing for BRAF, RAS, RET/PTC, and PAX8/PPARγ mutations may provide additional diagnostic information, as 97% of mutation-positive nodules are malignant, based on guidelines from the College of American Pathologists 1, 2