Background: Fine needle aspiration is the main diagnostic tool used to assess thyroid nodules.
Objectives: To correlate FNA cytology results with surgical pathological findings in two teaching medical centers across the Atlantic.
Methods: We retrospectively identified 484 patients at Hadassah Hebrew University Medical Center, Jerusalem and Mount Sinai Hospital, New York, by means of both preoperative FNA cytology and a final histopathological report. Results compared FNA diagnosis, histological findings and frozen section results (Mt. Sinai only).
Results: The sensitivity value of FNA at Hadassah was 83.0% compared with 79.1% at Mt. Sinai (NS). Specificity values were 86.6 vs. 98.5% (P < 0.05), negative predictive value 78.7 vs. 77.6% (NS) and positive predictive value 89.7 vs. 98.6% (P < 0.05), respectively. "Follicular lesion" was diagnosed on FNA in 33.1% of the patients at Hadassah and in 21.5% at Mt Sinai (P < 0.005) with a malignancy rate of 42.5 vs. 23.1% (P < 0.05), respectively. Frozen section was used in 190 patients at Mt. Sinai (78.5%) with sensitivity and specificity values of 72.3% and 100%. Frozen section results altered the planned operative course in only 6 patients (2.5%). Follicular carcinoma was diagnosed in 12 patients at Hadassah vs. 2 patients at Mt. Sinai (P < 0.05).
Conclusion: The sensitivity of FNA at the two institutions was comparable. While malignancy on frozen section is highly specific, it should be used selectively for suspicious FNA results. Follicular lesions and the rate of malignancy in such lesions were more common at Hadassah, favoring a more aggressive surgical approach.