Diagnostic Accuracy of Bethesda Classification of Thyroid Nodules at a Kenyan Hospital: A Retrospective Study

Abstract

Background: The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was developed to standardize the reporting of thyroid nodule fine-needle aspiration cytology (FNAC) results. The adoption of TBSRTC is based on the implied risk of malignancy per category, but this has shown wide variation in different regions worldwide. Aim: The aim of this study is to determine the diagnostic accuracy of the Bethesda classification of thyroid nodules in a Kenyan hospital. Methods: A retrospective longitudinal study examined FNAC and histopathology data of thyroid gland nodules at a Kenyan hospital from 2010 to 2019; specimens from 347 patients were found. An analysis was performed to determine the diagnostic accuracy of the Bethesda classification in detecting malignancy among these patients. Results: The malignancy rate was 16.1%. The risk of malignancy as per the Bethesda category was as follows: non-diagnostic— 19.6%, benign—6%, atypia of undetermined significance—20%, follicular neoplasm—16.7%, suspicious for malignancy—80%, and malignant—85.7%. The diagnostic properties of FNAC defining “malignant” and “suspicious for malignancy” categories as malignant were as follows: sensitivity—64.7%, specificity—97.6%, and accuracy—92.7%. Conclusion: The Bethesda classification had high diagnostic accuracy, with the risk of malignancy consistent with the Bethesda findings. Classifying malignancy as “malignant” and “suspicious for malignancy” yielded the most favorable diagnostic properties for FNAC.