Comparison of the collection approaches of 2 large thyroid fine-needle aspiration practices reveals differing advantages for cytology and molecular testing adequacy rates

Evaluating local thyroid cytopathology practices by molecular quality metrics: A multi-institutional study on 4651 FNAs with a focus on the role of the interventional cytopathologist

BACKGROUND

The diagnostic accuracy of thyroid fine-needle aspiration (FNA) can be highly influenced by the technical skills of the operator performing the procedure and by interobserver variability in microscopic interpretation. This is particularly true for the indeterminate categories. Recently, molecular testing has been proposed as an ancillary tool for monitoring the performance of different thyroid cytopathology practices. The objective of this multicenter study was to evaluate the quality of different local cytopathology practices by assessing the impact of interventional cytopathologists on FNA adequacy for molecular testing and the variations in mutation rates across different health care centers operating in the Campania region.

METHODS

The study included 4651 thyroid FNA samples diagnosed in different Southern Italian clinical laboratories belonging to the TIRNET (the Tiroide Network). FNA samples were collected by different proceduralists and were classified by local cytopathologists according to The Bethesda System for Reporting Thyroid Cytopathology. FNAs classified as atypia of undetermined significance, follicular neoplasm, suspicious for malignancy, and malignant were centralized for a real-time polymerase chain reaction-based, seven-gene test at the authors' institution.

RESULTS

Centers that employed interventional cytopathologists obtained fewer unsatisfactory FNA samples for molecular testing (11.3%) than centers that employed noncytopathologists (16.7%; p < .05). Furthermore, a significant variation in the mutation rate was observed in FNAs diagnosed by different local cytopathologists; indeterminate categories had the highest percentage of mutation rate variability among centers.

CONCLUSIONS

Interventional cytopathologists obtained higher yields of diagnostic material for molecular testing. Finally, the current results suggest that the variability in mutation rates among different centers may highlight the low reproducibility of microscopic criteria among cytopathologists, particularly for indeterminate cases.

Effect of a stylet on specimen sampling in thyroid fine needle aspiration: A randomized, controlled, non-inferiority trial

BACKGROUND

There is a cost advantage in using a needle without stylet over a needle with stylet in thyroid fine needle aspiration (FNA). This study aimed to elucidate the non-inferiority of thyroid FNA without a stylet (S-) to thyroid FNA with a stylet (S+) on specimen sampling.

METHODS

In this study, patients with thyroid nodules undergoing FNA were consecutively enrolled between May 2022 and July 2022. One experienced operator performed two punctures of each nodule with a stylet and without a stylet. Specimen adequacy was the primary outcome. Wald test was used for statistical analysis of the primary outcome. The difference in specimen adequacy between the two methods was expressed as a two-sided 95% confidence interval (CI). The S- method was considered non-inferior to the S+ method if the lower bound of the 95% CI of the S- minus S+ adequacy difference was greater than a predetermined non-inferiority margin of -10%.

RESULTS

A total of 149 patients (195 nodules) were enrolled in the study. A total of 167 of 195 nodules (85.64%) and 169 of 195 nodules (86.67%) were obtained adequate specimens using the S+ and S- methods, respectively. The difference in specimen adequacy (S- minus S+) between the two methods was 1.03% (95% CI, -5.83% to 7.88%). The lower bound 95% CI of the difference in specimen adequacy (-5.83%) was greater than the predetermined non-inferiority margin of -10%. The difference in the yield for malignancy was not significantly different between the two methods.

CONCLUSION

Thyroid FNA without a stylet is non-inferior to thyroid FNA with a stylet on specimen sampling.

Molecular Testing of Thyroid Fine-Needle Aspiration: Local Issues and Solutions. An Interventional Cytopathologist Perspective

Molecular testing has acquired a relevant role for diagnostic and prognostic stratification of indeterminate thyroid nodules. Besides the available commercial solutions marketed in the United States, various local testing strategies have been developed in the last decade. In this setting, the modern interventional cytopathologist, the physician who performs the both aspirate and the morphologic interpretation plays a key role in the correct handling of fine-needle aspiration (FNA) samples not only for microscopy but also for molecular techniques. This review summarizes experiences with local approaches to the molecular testing of thyroid FNA, highlighting the role of the modern interventional cytopathologist.