From which thyroid nodule (Fine Needle Aspiration) FNA should be taken in a patient with a 2x1cm mass on the right side and a 3x2cm mass on the left side?

FNA Should Be Taken from the Largest Nodule (Left Side 3x2 cm)

Fine needle aspiration (FNA) should be performed on the largest thyroid nodule, which in this case is the left-sided 3x2 cm nodule. 1

Rationale for Selecting the Largest Nodule for FNA

• The American College of Surgeons and the National Comprehensive Cancer Network recommend evaluation of thyroid nodules larger than 2 cm, even without suspicious features, due to the increased risk of malignancy 1
• The left-sided nodule (3x2 cm) exceeds this threshold and is significantly larger than the right-sided nodule (2x1 cm)
• A nodule size of 3 cm is considered a worrisome feature associated with a 3-times greater risk of malignancy compared to smaller nodules 2
• Larger nodules contain sufficient fluid to perform FNA with adequate cytological evaluation 2

Evidence Supporting This Approach

• The Thyroid Imaging Reporting And Data Systems (TIRADS) guidelines use nodule size as a criterion for recommending FNA, with larger nodules generally warranting more attention 2
• Current guidelines from the International Journal of Surgery strongly recommend that all patients with suspicious thyroid nodules undergo puncture biopsy to confirm pathological diagnosis, with FNA as the preferred method 1
• FNA is recognized as the most accurate and cost-effective method for evaluating thyroid nodules and remains the gold standard for preoperative diagnosis of thyroid malignancy 2

Size Considerations in Thyroid Nodule Evaluation

• While some studies suggest that nodule size alone is a poor predictor of malignancy 3, larger nodules (>2 cm) warrant evaluation due to their clinical significance 1
• The risk of false-negative FNA results increases significantly for nodules larger than 4 cm (up to 50%), but is relatively low (1.3-13.3%) for nodules in the 1-4 cm range 4
• The accuracy of FNA for nodules between 2-4 cm (which includes the left nodule in this case) is approximately 94.7%, making it a reliable diagnostic approach 4

Important Clinical Considerations

• FNA should be performed under ultrasound guidance to improve accuracy and ensure proper sampling of the nodule 1, 5
• If the cytology results are indeterminate, a repeat FNA or core needle biopsy may be necessary 1
• While both nodules are larger than 1 cm (the typical threshold for considering FNA), prioritizing the larger nodule is the standard approach when multiple nodules are present 2, 1
• If the FNA of the larger nodule yields benign results but clinical suspicion remains high, the second nodule can be evaluated in a subsequent procedure 2

Potential Pitfalls to Avoid

• Attempting to sample both nodules simultaneously may lead to inadequate sampling and inconclusive results 1
• Focusing on the smaller nodule first goes against standard clinical practice and may delay diagnosis if the larger nodule harbors malignancy 1
• Follicular neoplasms may be difficult to definitively diagnose by FNA alone, potentially requiring histological examination 1
• Not performing FNA at all would be inappropriate given that both nodules exceed 1 cm and warrant evaluation 2, 1