From the Guidelines
A TIRADS 4 thyroid nodule should be biopsied when it measures ≥1.0 cm in size. These moderately suspicious nodules carry approximately a 5-20% risk of malignancy, making tissue sampling important for definitive diagnosis 1. For nodules between 1.0-1.4 cm, fine needle aspiration (FNA) biopsy is recommended, while those ≥1.5 cm may warrant either FNA or core needle biopsy depending on clinical context. The biopsy provides cellular material that can be analyzed for malignant features, helping to determine appropriate management.
Some key points to consider when deciding to biopsy a TIRADS 4 thyroid nodule include:
- Nodule size: ≥1.0 cm is the general threshold for biopsy consideration 1
- Ultrasound features: concerning features such as irregular margins, microcalcifications, or taller-than-wide shape may warrant biopsy even for smaller nodules 1
- Risk factors: prior head/neck radiation or family history of thyroid cancer may increase the likelihood of malignancy and justify biopsy 1
- Clinical context: the decision to perform FNA or core needle biopsy may depend on the individual patient's situation and the suspected type of thyroid cancer 1
Following biopsy, management decisions will depend on cytology results, ranging from simple monitoring to surgical intervention based on the Bethesda classification system findings. It is essential to weigh the benefits of biopsy against the potential risks and costs, particularly given the high rate of indolent thyroid cancers and the potential for overdiagnosis 1.
From the Research
Biopsy of Thyroid Nodules
- The decision to biopsy a thyroid nodule is typically based on the nodule's characteristics and the patient's overall health, as discussed in 2.
- The American College of Radiology (ACR) Thyroid Imaging, Reporting and Data System (TI-RADS) is a widely used system for evaluating thyroid nodules and determining the need for biopsy, as described in 3.
TI-RADS Scoring System
- The TI-RADS scoring system assigns a score to each nodule based on its ultrasound characteristics, with higher scores indicating a higher risk of malignancy, as explained in 3.
- A study published in 4 found that the TI-RADS score was positively correlated with the risk of malignancy, with higher scores indicating a higher risk of cancer.
- The study in 4 also found that a TI-RADS score of 4 (TR4) was the optimal cutoff point for predicting malignancy, with 80.3% sensitivity and 60.8% specificity.
Biopsy of TI-RADS 4 Nodules
- Based on the study in 4, a thyroid nodule with a TI-RADS score of 4 (TR4) has a 50.3% risk of malignancy, indicating that biopsy is likely necessary to determine the presence of cancer.
- The study in 2 discusses the importance of fine-needle aspiration biopsy (FNA) in evaluating thyroid nodules and determining the need for surgical removal.
- Another study in 5 found that ultrasound-guided FNA was not necessary for all patients, but it may be beneficial for nonpalpable, predominantly cystic, or previously nondiagnostic nodules.
Procedure and Risks
- The procedure for biopsy of a thyroid nodule typically involves fine-needle aspiration biopsy (FNA), which can be performed under ultrasound guidance, as discussed in 6 and 5.
- The study in 6 found that patients taking novel oral anticoagulants (NOACs) can safely undergo ultrasound-guided FNA without discontinuing their anticoagulant therapy.