Thyroid nodules are common growths within the thyroid gland, a butterfly-shaped organ located at the base of your neck. While finding a nodule can be concerning, the vast majority are benign, meaning non-cancerous. To help doctors classify these nodules and guide further evaluation, a standardized system called TIRADS (Thyroid Imaging Reporting and Data System) is used to interpret ultrasound findings and determine appropriate next steps.
What is TIRADS 4?
TIRADS 4 indicates a “moderately suspicious” thyroid nodule based on its ultrasound characteristics. This classification means the nodule exhibits certain features that raise a concern for malignancy, but it does not confirm cancer. The estimated risk of malignancy for a TIRADS 4 nodule ranges from 5% to 20%.
Specific ultrasound features contribute to a TIRADS 4 classification. These include a solid composition, where the nodule is mostly dense tissue rather than fluid-filled. Hypoechogenicity, meaning the nodule appears darker than the surrounding thyroid tissue on ultrasound, is another concerning feature.
Irregular or lobulated margins, where the edges of the nodule are uneven or bumpy, also increase suspicion. The presence of microcalcifications, which are tiny bright spots within the nodule, and a “taller-than-wide” shape (meaning the nodule is taller than it is wide on a transverse view) are additional features that contribute to a higher TIRADS score. A nodule can be classified as TIRADS 4 even if it is relatively small, with some studies suggesting that nodules with a diameter lower than 12 mm are highly suspicious for malignancy.
Next Steps After a TIRADS 4 Finding
Following a TIRADS 4 classification, the primary next step is a fine needle aspiration (FNA) biopsy. This procedure involves using a very thin needle, guided by ultrasound, to collect a small sample of cells from the thyroid nodule. The ultrasound guidance helps ensure the needle accurately targets the nodule.
The purpose of an FNA biopsy is to obtain cells for pathological examination under a microscope. This examination helps determine if the nodule is benign, suspicious, or malignant. For TIRADS 4 nodules, an FNA biopsy is recommended for nodules measuring 1.0 cm or larger.
Understanding Your Results and Management
The results of the FNA biopsy for a TIRADS 4 nodule will guide the subsequent management plan. If the biopsy indicates the nodule is benign, meaning non-cancerous, continued monitoring with ultrasound over time is often recommended. This typically involves follow-up ultrasounds at intervals such as 12-24 months.
If the biopsy results are suspicious or indeterminate, further evaluation may be necessary. This could involve a repeat biopsy to obtain more samples, molecular testing of the nodule cells to assess for specific genetic markers, or surgical removal for a definitive diagnosis. In cases where the biopsy confirms the nodule is malignant, indicating cancer, discussions will typically focus on surgical removal of the thyroid gland, known as thyroidectomy, and other potential treatment options if needed. Management plans are highly individualized and require thorough discussion with a healthcare provider to determine the best course of action.