Repetition of thyroid fine-needle aspiration cytology after an initial nondiagnostic result: Is there an optimal timing?

ABSTRACT

INTRODUCTION: It is suggested to wait at least 3 months to repeat a fine needle aspiration cytology (FNAC) to avoid possible inflammatory cytological changes induced by a previous procedure. This study evaluated the influence of the interval between 2 FNACs in a cohort with a previous non-diagnostic (ND) FNAC. We analysed the occurrence of ND or atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) results in the second FNAC, based on the intervals between procedures. PATIENTS AND METHODS: Retrospective study (2017-2020) including thyroid nodules with a ND result, subjected to another FNAC. Demographic, clinical and echographic data, interval between FNACs and their results were collected. We considered the intervals ≤/>3 months and ≤/>6 months. Second FNAC results were classified as ND, AUS/FLUS or diagnostic (including the other Bethesda categories). RESULTS: Included 190 nodules (190 patients - 82.1% women, mean age 60±13.7 years) with a first ND FNAC. The second FNAC results were ND in 63 cases, AUS/FLUS in 9 and diagnostic in 118 cases. There were no statistical differences in FNAC results performed≤3 months (13 ND, 2 AUS/FLUS, 19 diagnostic) vs >3 months (50 ND, 7 AUS/FLUS, 99 diagnostic; p=0.71). Similarly, there were no statistical differences considering a longer time interval ≤6 months (32 ND, 3 AUS/FLUS, 59 diagnostic) vs >6 months (31 ND, 6 AUS/FLUS, 59 diagnostic; p=0.61). CONCLUSIONS: Time interval between FNACs was not relevant to the final cytological result. Early FNAC repetition did not increase the cases of ND or AUS/FLUS.