Differences in cytopathologist thyroid nodule malignancy rate

Objectives:: The accuracy of a cytological diagnosis obtained by fine needle aspiration is influenced by several factors including the technique used and the experience of both the aspirator as well as the cytologist. In this project we planned to evaluate the interobserver differences of thyroid nodule cytopathology in our medical centre. Methods:: The study was conducted using retrospective pathology reports from a single academic centre from August 2013 to September 2017. We compared the sensitivity, specificity, negative and positive predictive values, malignancy rates, and accuracy of two cytopathologists who evaluated thyroid nodules. Results:: We included 287 fine needle aspirations of thyroid nodules in the study. Approximately one fifth (18.5%) of patients had surgery and the rate of malignancy was 40%. There was a similar frequency of use of all thyroid Bethesda system (TBS) categories with the exception of TBS 3 (8.0% and 21.2%, P =.01). As a consequence, the malignancy rate was different in TBS 3 category (40% vs 17%, P =.545). Conclusions:: There are interobserver differences in the evaluation of thyroid nodules. Clinicians should be aware of such differences because they affect the malignancy rate in each TBS category.