The interobserver reproducibility of thyroid cytopathology using Bethesda Reporting System: Analysis of 200 cases

Objective: To determine interobserver reproducibility of thyroid cytopathology in cases of thyroid fine needle aspirates. Methods: The retrospective, descriptive study, was conducted at the Foundation University Medical College, Islamabad, using cases related to period between 2009 and 2011. A total of 200 cases of fine-needle aspirations were retrieved from the archives. Three histopathologists independently categorised them into 6 groups according to Bethesda reporting system guidelines without looking at previous reports. Kappa statistics were used for analysis of the results on SPSS 17. Results: Of the 200 patients, 194 (97%) were females and 6 (3%) were males. The overall mean age of patients was 46+-20 years. Kappa value calculated for observer-1 and observer-2 was 0.735; for observer-1 and observer-3, 0.841; and for observer-2 and observer-3, 0.838, showing substantial interobserver agreement. Histopathological correlation was available, for 39(19.5%). Of these cases, 5(13%) were non-diagnostic, 20(51%) benign, 2(5%) atypia of undetermined significance/follicular lesion of undetermined significance, 6(15%) follicular neoplasm, 1(3%) suspicious for malignancy, and 5(13%) malignant. Conclusions: Good overall interobserver agreement was found, but discordance was seen when certain categories were analysed separately. (author)