Fine-needle aspiration cytology of nodular thyroid lesions: A 1-year experience of the thyroid cytopathology in a large regional and a University Hospital, with histological correlation

Abstract

Background: Fine-needle aspiration cytology (FNAC) plays an important role in evaluation of nodular thyroid lesions and in planning appropriate management. Aim: the aim of the study is to reinterpret the FNAC diagnosis using the new 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) and explore its utility and to review the accuracy by correlating with histopathology and analyze the distribution of thyroid lesions. Settings and Design: A retrospective study for a period of 1 year will be undertaken, and all the cases of thyroid FNAC during the study period will be included in the study. Materials and Methods: All FNACs of the thyroid, which were done during the year 2011, were retrieved. The results of adequate FNAC samples were correlated with the histological diagnoses in 50 cases. Statistical Analysis: the statistical analysis was performed using MedCalc Statistical Software Results: About 592 cases were included in the study, after recategorization according to the TBSRTC, Bethesda I – 2 cases (0.33%), Bethesda II – 473 cases (79.8%), Bethesda III – 54 cases (9.1%), Bethesda IV – 23 cases (3.8%), Bethesda V – 3 cases (0.5%), and Bethesda VI – 37 cases (6.25%). The false-negative rate is 9%, accuracy rate is 91%, and rate of malignancy in atypical lesions is 53.3%, with overall rate of accuracy of 61.5%. The incidence of microcarcinoma was 4/50 (8%). Conclusions: The distribution of thyroid lesions in our institute is similar to that seen elsewhere. The rate of malignancy in indeterminate lesions was 33.33%. FNA has a low false-negative rate for diagnosis of thyroid malignancy; however, controversy exists regarding the accuracy of FNA for nodules smaller than 1 cm. The nomenclature change of follicular variant of papillary thyroid carcinoma to noninvasive follicular thyroid neoplasm with papillary-like nuclear features has led to necessary changes in definitions of various categories in 2017 TBSRTC as well and is discussed in this paper.