Endocrine Abstracts

Aim: To determine whether early repeat fine needle aspiration biopsy(FNAB) has an effect on adequate or atypia of undetermined significance/follicular lesion of undetermined significance(AUS/FLUS) cytology rates in thyroid nodules with inadequate or AUS/FLUS in the first FNAB.

Method: Nodules of patients who underwent repeat biopsy due to insufficient or AUS/FLUS cytology between 2019-2022 were included. Demographic data of the patients and ultrasonographic, cytological and histopathological results of the nodules were recorded. Additionally, the time between the two biopsies was noted. In nodules with two FNAB results, the first was called initial, and the second was called rebiopsy. In nodules with more than two FNAB results, the time between each consecutive results was evaluated separately, and for these nodules, again first result was called initial and the second was called rebiopsy for each biopsy period of the nodule. Seven different paired groups were formed according to the time between two consecutive biopsies;before and after 1 month,45 days,2 months,3 months,6 months,9 months,12 months. The groups were compared in terms of adequate or AUS/FLUS cytological results.

Results: 972 nodules of 546 patients who underwent FNAB at least twice were included. The mean age of the patients was 51±12, and the female sex ratio was 79.1% (n=432). FNAB was performed 2 times for 573,3 times for 310, 4 times for 73, 5 times for 13 and 6 times for 3 of the nodules. A total of 2984 cytology results were evaluated. Accordingly,1026 (68.8%) of the initial biopsies were inadequate and 466 (31.2%) were AUS/FLUS. Rebiopsy results are shown in the table. There were no differences in adequate or AUS/FLUS rebiopsy results according to the different time interval groups(P>0.05 for all). When 1026 samples with inadequate initial FNAB were considered as a separate group, to perform rebiopsy before or after any time interval had no effect on adequate or AUS/FLUS results. Similar results were obtained when a subgroup was created for samples with initial AUS/FLUS cytology(P>0.05 for all). Also, there was no cut-off time for an adequate or AUS/FLUS rebiopsy result.

Conclusions: In patients with inadequate or AUS/FLUS initial biopsy, the rate of adequate or AUS/FLUS cytology results at rebiopsy did not vary with the timing of repeat biopsy. As recommended in the ATA guideline, there is no need to wait 3 months for a repeat biopsy. In patients with suspicious nodules in terms of malignancy, biopsy might be repeated before 1 month.