LAUSR

Simple Summary Thyroid nodules of category III in the Bethesda system do not constitute a uniform group, so it is still a challenge to produce a recommendation for the management of patients with such nodules. The aim of the study was to examine the benefits of the joint use of repeat FNA and a sonographic risk stratification system in category III nodules in relation to the kind of atypia: cytologic/nuclear vs. architectural. Our results indicate that in both kinds of these nodules, the joint evaluation of repeat FNA outcome and sonographic risk of malignancy shows better effectiveness than any of these methods separately. Such a combination allows the identification of patients with a high risk of malignancy as well as a group of patients in which surgical treatment may be safely put aside. Abstract The aim of the study was to examine the benefits of the joint use of repeat FNA (rFNA) and EU-TIRADS in category III nodules in relation to the kind of atypia: nuclear vs. architectural (denoted by AUS and FLUS respectively). The study included 127 AUS and 1739 FLUS nodules with a known category of EU-TIRADS. Repeat FNA was performed in 82 AUS and 934 FLUS nodules of which 57 and 515 were excised, respectively. AUS nodules had higher malignancy risk than FLUS nodules. EU-TIRADS showed higher accuracy for AUS nodules, the opposite to rFNA, that had higher accuracy for FLUS nodules. The combined criterion for AUS nodules (at least rFNA-V or EU-TIRADS-4) maximized sensitivity (92.3%) with acceptable specificity (70.0%); OR: 28.0. In the case of FLUS nodules, the combined criterion (rFNA-V or EU-TIRADS-5) maximized specificity (95.2%) with 57.7% sensitivity and a low percentage (13.9%) of positive nodules, OR: 27.0. In both types of nodules, the low risk category in EU-TIRADS and benign result of rFNA excluded cancer. Concluding, category III nodules with and without nuclear atypia differ in their risk of malignancy and, consequently, diagnostic criteria adopted for the evaluation of these nodules with rFNA and EU-TIRADS should be specific to AUS and FLUS nodules.