Endocrine Abstracts

Background: The BSRTC aimed to standardize thyroid cytopathology reporting while enabling stratification of risk of malignancy (ROM) in thyroid nodules. Observational studies have demonstrated varying ROM for the Bethesda III and IV categories, further affected by the recent exemption of NIFTP. Finally, molecular testing is becoming a reasonable alternative for evaluating ROM in categories III and IV.

Objective: To retrospectively establish the use of Bethesda categories III and IV in specimens obtained from FNAs at Tel Aviv Sourasky Medical Center over a 3 year period, to assess the ROM in these categories in the era of molecular testing and NIFTP, and to examine clinical correlates that might affect the ROM.

Methods: Aspirated thyroid nodules between January 2013 and December 2015 were reviewed. Files of patients with nodules classified as category III and IV were searched for downstream surgical procedures, repeat FNA and/or Afirma^® gene classifier testing, in order to determine their outcome. Confirmed NIFTPS were considered benign lesions. Sonographic characteristics and potential clinical risk factors for malignancy were evaluated for category III and IV nodules.

Results: Of 3701 nodules aspirated on 2674 subjects (80% women/20% men, age 56.7±15.5 y), 6.5% were Bethesda-I, 72.8% Bethesda-II, 7.7% Bethesda-III, 3.6% Bethesda-IV, 2.3% Bethesda-V, and 7.2% Bethesda-VI. A diagnostic outcome was available for 128 of the 284 category III nodules: 18 (14.0%) were malignant (16.4% if NIFTP included), and 109 (86.0%) were benign. The outcome was known for 60 of the 132 category IV nodules, 17 (28.3%) were malignant (31.7% if NIFTP included), and 43 (71.7%) were benign. Male gender and smoking were significant and independent risk factors for malignancy in Bethesda III, but not in Bethesda IV nodules. Age, country of birth, family history of thyroid cancer, nodule size, and a cumulative score of 5 suspicious sonographic characteristics were not predictive of malignancy in either category.

Conclusion: The distribution of the various Bethesda categories in our study, and specifically categories III and IV, was consistent with previous published reports. The ROM for Bethesda III and IV nodules was also in line with recent reports. Exclusion of NIFTP from malignancy did not significantly affect these figures. Although we identified several factors that increased the ROM, their predictive value was not powerful enough to be acted upon. Better molecular tools are needed to further reduce the number of unnecessary surgeries in this age of epidemic of incidentally discovered thyroid nodules.