The Impact of Non-invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features on the Risk of Malignancy in The Bethesda System for Reporting Thyroid Cytopathology Categories

  • Background:
    The introduction of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has been shown to decrease the risk of malignancy (ROM) in different categories of The Bethesda System for Reporting Thyroid Cytopathology. This might alter the management of patients with thyroid nodules. We aim to correlate the cytological diagnosis with the histological diagnosis to establish the ROM of all Bethesda system categories after the introduction of NIFTP.
    This study is a retrospective cohort study. Data of fine needle aspiration cytology (FNAC) was collected from 2013-2017 at King Abdullah Medical City in Jeddah. The ROM was calculated with and without NIFTP in all cases.
    The overall number of collected cases was 1066 FNAC specimens, of which 281 had surgical correlation. Our cases included 18 (6.4%) unsatisfactory for diagnosis (US), 109 (38.8%) benign, 28 (9.9%) atypia/follicular lesion of undetermined significance (AUS/FLUS), 39 (13.8%) follicular neoplasm or suspicion for follicular neoplasm (FN/SFN), 20 (7.1%) suspicion for malignancy (SM), and 67 (23.8%) malignant (POM) cases. After considering NIFTP, the ROM has decreased from 38.8% to 27.7% (P = .2388) in US, from 21.1% to 11.9% (P = .0343) in benign, from 50% to 39.2% (P = .2089) in AUS/FLUS, from 53.8% to 33.3% (P = .0336) in FN/SFN, from 85% to 75% (P = .2147) SM, and from 95.5% to 88% (P = .0582) in POM.
    Our results showed that introducing NIFTP will significantly impact the ROM of thyroid FNAC in both benign and FN/SFN categories in our institution.


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