Analysis of histological features and recurrence risk assessment of papillary thyroid carcinoma according to presurgery FNAC category

Identifying preoperatively cases of more indolent papillary thyroid carcinoma (PTC)could be of high interest. The aim of this study was to verify previously published data on the prognostic value of fine needle aspiration cytology (FNAC)in PTC, also comparing findings from high-volume (HV)and low-volume (LV)institutions. From January 2022 to June 2024, the institutional database of the endocrinological surgery unit of Sant'Eugenio Hospital (Rome, Italy)was retrospectively reviewed to select patients who underwent thyroid surgery for PTC. To evaluate the prognostic value of presurgical FNAC, all histological features and the ATA risk of the study groups were compared. Later, data of patients entirely managed at our institution, considered as an HV institute, were compared with that of cases operated at our institution following FNAC performed LV centres.The 159 PTC nodules included were classified as TIR3B (20.1%),TIR4 (32.7%),and TIR5 (47.2%).The distribution of FNAC report between HV and LV was different (p = 0.01). The presence of lymph node metastasis (p = 0.004), and peri-thyroid tissue invasion (p = 0.02)increased according to the FNAC category. Significant difference among the three FNAC categories was also observed in PTC subtype (p = 0.006)and Hashimoto's thyroiditis (p = 0.02).In addition, a significant different trend was found in ATA risk assessment, being the risk of recurrence more prevalent according to the FNAC category (p = 0.008). According to the second study aim, the higher prevalence of low-risk cases in TIR3B was confirmed in both HV (p = 0.04) and LV (p = 0.03)subgroups.PTCs with preoperative TIR3B have different histological features and ATA risk assessment with respect to cases with presurgical FNAC of TIR4/5.Particularly, PTC from TIR3B should have a pattern of more indolent cancers. As non-negligible extension, this data is not influenced by the institutional setting with high or low thyroid-FNAC volume.