False-negative fine-needle aspiration of thyroid nodules cannot be attributed to sampling error alone.

Area of Science:

• Endocrinology
• Surgical Pathology
• Cytopathology

Background:

• Fine needle aspiration (FNA) is a common diagnostic tool for thyroid nodules.
• False-negative FNA results can lead to delayed diagnosis and treatment of thyroid cancer.
• Determining the primary cause of false-negative results is crucial for improving diagnostic accuracy.

Purpose of the Study:

• To investigate whether sampling error is the predominant factor contributing to false-negative FNA diagnoses in thyroid nodules.
• To identify other potential factors associated with false-negative FNA results.

Main Methods:

• Retrospective review of patients who underwent preoperative FNA for thyroid nodules between 1994 and 2008.
• Comparison of FNA results with subsequent surgical pathology findings.
• Analysis of variables including nodule characteristics (size, number) and presence of thyroiditis.

Main Results:

• The overall false-negative rate for FNA, excluding microcarcinomas, was 4% (19/479).
• Sampling error accounted for only 21% (4/19) of false-negative cases.
• Factors associated with false-negative results included solitary nodules (53%), large nodule size ≥4 cm (53%), and underlying thyroiditis (33%).
• Delayed diagnosis necessitated completion thyroidectomy in 47% of patients initially treated with lobectomy alone.

Conclusions:

• Sampling error is an infrequent cause of false-negative thyroid FNA results.
• The findings indicate intrinsic limitations in the cytological evaluation of thyroid nodules.
• Further research into improving the sensitivity of thyroid FNA interpretation is warranted.