False Negative Rate of Thyroid FNA and Clinical Implications

Guideline Recommendations and Clinical Implications

• The National Comprehensive Cancer Network (NCCN) explicitly warns that false-negative results are sometimes obtained with FNA, and a reassuring FNA should not override concerns in the presence of worrisome clinical findings, particularly for patients with suspicious ultrasound features or high-risk nodule characteristics, such as large cystic/solid nodules or subcentimeter nodules 1
• Expert pathology review at the treating institution is critical, as FNA sensitivity varies by cancer type and institutional expertise, with a focus on accurate diagnosis and appropriate management of thyroid nodules, including consideration of repeat FNA or diagnostic thyroid lobectomy for high-risk scenarios 1, 2
• Medullary carcinoma may require additional immunohistochemical studies (calcitonin staining) to confirm diagnosis, as it can be missed on routine cytology, highlighting the importance of thorough diagnostic evaluation and consideration of clinical context, including patient history and physical examination findings 1