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

To determine interobserver reproducibility of thyroid cytopathology in cases of thyroid fine needle aspirates.

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.

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.

Good overall interoberver agreement was found, but discordance was seen when certain categories were analysed separately.