Thyroid fine-needle aspiration: does case volume affect diagnostic yield and interpretation?

OBJECTIVE To evaluate the effect of case volume on the diagnostic yield and interpretation of thyroid fine-needle aspiration (FNA). DESIGN Retrospective case series. SETTING An academic tertiary referral center and 2 community hospital centers. PATIENTS Data were retrospectively reviewed for all consecutive patients undergoing thyroid FNA at these institutions during the 2009 calendar year. MAIN OUTCOME MEASURES Differences in diagnostic distribution and yield among pathologists and clinicians of differing case volume. RESULTS A total of 790 patients underwent thyroid FNA, with the results interpreted as benign (479 [60%]), atypical (166 [22%]), malignant (9 [1%]), or nondiagnostic (136 [17%]). The FNAs were performed by 134 physicians and interpreted by 16 pathologists with varying case volumes. Low-volume pathologists (<50 FNAs interpreted) were more likely to report atypical FNAs (32% vs 13%; P < .001) and less likely to call FNAs benign (50% vs 70%; P < .001) compared with high-volume pathologists (≥50 FNAs interpreted), and compared with expected normative data (benign, P < .001; atypical, P < .001). Atypical FNA findings reported by low-volume pathologist were more likely to yield benign permanent results than those read by high-volume pathologists (64% vs 42%; P < .02). Low-volume clinicians (<20 FNAs performed) were not more likely to perform nondiagnostic FNAs compared with high-volume clinicians (≥20 FNAs performed) (16% vs 15%; P = .47). CONCLUSIONS Case volume significantly influences the pathologic interpretation of thyroid FNA, as low-volume pathologists report more atypical and fewer benign FNA results. Case volume did not have a significant impact on diagnostic yield, because thyroid FNAs performed by low-volume clinicians did not result in more frequent nondiagnostic results compared with those performed by high-volume clinicians.