Management of a 1.9 cm TI-RADS 3 Thyroid Nodule
Fine needle aspiration (FNA) is the most appropriate next step in managing this 49-year-old man with a 1.9 cm thyroid nodule classified as TI-RADS grade 3.
Rationale for FNA
The decision to perform FNA for thyroid nodules depends on several factors, including:
- Nodule size: At 1.9 cm, this nodule exceeds the size threshold for biopsy
- TI-RADS classification: TI-RADS 3 indicates intermediate suspicion
- Patient factors: 49-year-old male with no reported symptoms
TI-RADS Classification System
The American College of Radiology (ACR) TI-RADS system stratifies thyroid nodules based on ultrasound features to determine which nodules warrant biopsy 1. For TI-RADS 3 nodules (low-intermediate suspicion):
- Nodules ≥1.5 cm should undergo FNA
- Nodules 1.0-1.4 cm should be followed with ultrasound
- Nodules <1.0 cm generally require no follow-up
Since this patient's nodule is 1.9 cm, it exceeds the 1.5 cm threshold for FNA according to ACR TI-RADS guidelines.
Management Algorithm
- For TI-RADS 3 nodules ≥1.5 cm: Perform FNA
- For TI-RADS 3 nodules 1.0-1.4 cm: Ultrasound follow-up
- For TI-RADS 3 nodules <1.0 cm: No further evaluation
Evidence Supporting FNA
Multiple guidelines support FNA for nodules of this size and risk category:
- The American Thyroid Association recommends FNA for nodules >1 cm with intermediate suspicion features 2
- Research has shown that TI-RADS 3 nodules have approximately 1.7-2% risk of malignancy when NIFTP (noninvasive follicular thyroid neoplasm with papillary-like nuclear features) is included 3
Why Not Other Options?
Why not thyroid lobectomy?
Proceeding directly to lobectomy without cytologic diagnosis would be overly aggressive for a TI-RADS 3 nodule, which has a relatively low risk of malignancy.
Why not repeat ultrasound in 6-12 months?
While surveillance is appropriate for smaller TI-RADS 3 nodules (1.0-1.4 cm), this 1.9 cm nodule exceeds the size threshold for immediate FNA 1.
Why not TSH level and genetic testing?
While TSH measurement may be useful, it's not the most appropriate next step. Genetic testing is typically reserved for indeterminate cytology results after FNA, not as an initial diagnostic approach.
Clinical Pearls and Pitfalls
- Pearl: TI-RADS scoring helps standardize management of thyroid nodules and reduces unnecessary biopsies while identifying clinically significant cancers
- Pitfall: Relying solely on nodule size without considering ultrasound characteristics may lead to unnecessary procedures
- Caution: Even with a TI-RADS 3 classification, the risk of malignancy is not zero (approximately 2%), justifying FNA for nodules ≥1.5 cm
Conclusion
Based on current guidelines and the nodule's characteristics (1.9 cm, TI-RADS 3), FNA is the most appropriate next step in management to determine if this nodule requires further intervention or can be safely monitored.