Accuracy of prior cytology versus intraoperative consultation in predicting the final diagnosis of thyroid specimens

Abstract

Abstract Introduction/Objective The aim of this study was to assess the accuracy of preoperative cytology and the additional contribution of intraoperative frozen section in predicting the final diagnosis of thyroid surgical specimens. Methods/Case Report A retrospective search was conducted for cases that underwent pre-surgical cytology of thyroid surgical specimens received from January 2017 to June 2022. A total of 99 cases were evaluated which were grouped into six categories according to the Bethesda system. The cytology results were compared with the corresponding frozen section and permanent section diagnoses. Indeterminate and discordant cases were further evaluated with molecular tests. Results (if a Case Study enter NA) Among the 99 cases, preoperative cytologic diagnoses were as follows: 1 was nondiagnostic, 9 were benign, 7 were AUS/FLUS, 3 were FN/SFN, 7 were suspicious for malignancy, and 72 were malignant. Using Bethesda categories V and VI as cytology “positive” cases and Bethesda category II as cytology “negative” cases, the sensitivity and specificity of cytology were 99% and 100%, respectively. The positive predictive value was 100%. The negative predictive value was 89%, which was affected by sampling error. Intraoperative frozen section was performed on 31 cases. In 4 indeterminate cytology cases (Bethesda III, IV), frozen section diagnosis was benign in 1 (confirmed on final) and remained indeterminate in 3 cases (3 benign on final). All 3 dual indeterminate cases showed a follicular pattern; molecular tests were predictive of the final diagnosis in these cases. All 21 malignant frozen section diagnoses had positive cytology. Conclusion Cytology has high sensitivity and specificity, making it a valuable preoperative tool in thyroid surgery. Practically, intraoperative frozen section has limited value in thyroid nodules classified as Bethesda categories V and VI. Additional evaluation may be helpful for cases classified as uncertain Bethesda categories. For follicular patterned lesions, frozen section may have less value.