Abstract
BackgroundFine-needle aspiration cytology (FNAC) has become a well-established modality in the diagnosis, staging and follow-up of thyroid nodules. FNAC outcomes are routinely classified using the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), facilitating appropriate clinical management. Bethesda categories III and IV encompass varying risks of malignancy. This retrospective study established a possible association between these cytological categories and malignancy rates in patients treated at a single institution.MethodsOver a 6-year period, 11,627 FNAC procedures were performed on thyroid nodules. Of these, 814 (59.63%) patients were submitted to thyroidectomy. The nodules of 108 patients were classified as Bethesda category III and 47 patients as Bethesda category IV. Patient data were reviewed to establish a correlation between the FNAC results and the final histopathological analyses.ResultsThe rates of malignancy among patients who underwent surgery were 25% for category III and 27.6% for category IV, with no significant differences between categories (p = 0.67). The pathological parameters of malignant nodules, namely tumour type, size, encapsulation, invasion into the thyroid capsule, extrathyroidal extension and lymphovascular invasion did not significantly differ between the groups (p > 0.05).ConclusionsThis paper provides a more precise correlation of malignancy rates with thyroid nodules classified as Bethesda categories III and IV, as our findings are comparable to the literature, giving malignancy rates ranging from 10 to 30% for category III and 25–40% for category IV. Use of the BSRTC is heterogeneous across institutions, and there is some degree of subjectivity in the distinction between categories III and IV; therefore, it is crucial to estimate the rates of malignancy at each institution. Molecular assays are of increasing importance in determining the need for surgical intervention for thyroid lesions. Gene expression assays using FNAC material may demonstrate a high predictive value for cytologically indeterminate thyroid nodules diagnosed as Bethesda classes III and IV.
Highlights
Fine-needle aspiration cytology (FNAC) has become a well-established modality in the diagnosis, staging and follow-up of thyroid nodules
FNAC is widely used in clinical diagnosis, cytologically indeterminate thyroid nodules continue to present a diagnostic challenge for pathologists
Overall, 4.2% (2630/11627) of all thyroid FNAs performed during the study period were classified as atypia of undetermined significance” (AUS)/ follicular lesion of undetermined significance” (FLUS) (Fig. 1) and 6.8% (1716/11627) were classified as Follicular neoplasm / suspicious for follicular neoplasm (FN/SFN) (Fig. 2), in accordance with the Bethesda System for Reporting Thyroid Cytopathology guidelines
Summary
Fine-needle aspiration cytology (FNAC) has become a well-established modality in the diagnosis, staging and follow-up of thyroid nodules. Fine-needle aspiration cytology (FNAC) has become a well-established diagnostic technique It accelerates the assessment of cellular morphologic features of thyroid nodules from which the malignant risk can be determined. There are controversial data about the risk of malignancies, recurrence and clinical management of nodules in Bethesda categories III and IV, as the reported risks of malignancy vary significantly, from 10 to 30% to 25–40% (including noninvasive follicular thyroid neoplasm with papillary-like nuclear features [NIFTP]), respectively [4]. This leads to different approaches to choosing the best therapies. A crucial advantage of the Bethesda III category is that FNAC specimens may need to be reevaluated, and in the case of a suspected follicular carcinoma, rebiopsy and operative intervention should be considered [4]
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