Thyroid cytopathology with fine needle aspiration in the era of NIFTP： A retrospective analysis of 2 838 cases

Abstract:

Objective：To investigate the role of the new Bethesda System for Reporting Thyroid Cytopathology（TBSRTC） in the diag－nosis of thyroid disease using fine needle aspiration（FNA）. Methods：A retrospective analysis was performed for the data on thyroid FNA cytopathology and postoperative pathology of 2 838 patients treated in our hospital from January 2015 to April 2017. Results：Among the 2838 thyroid FNA specimens，101 were considered unsatisfactory；1 268 were benign lesions；195 were evaluated as atypia of undetermined significance/follicular lesion of undetermined significance；5 were follicular tumor/suspected follicular tumor；401 were suspected malignancies，among which 2 were diagnosed with non-invasive follicular thyroid neoplasm with papillary-like nuclear features（NIFTP）；868 were malignant lesions. A total of 791 patients underwent surgical treatment，and the results showed that the risk of malignancy in the six categories was 0%，34.4%，71.4%，66.7%，69%，and 97%，respectively. One case of follicular tumor/suspected follicular tumor diagnosed by cytopathology was confirmed to be well-differentiated tumor of uncertain malignant potential by postop－erative pathology. Two cases of NIFTP were confirmed by surgery and 3 cases of malignancies diagnosed by cytopathology were proved to be hyalinizing trabecular tumor by postoperative pathology. Conclusion：Thyroid cytopathology reveals a low incidence rate of bor－derline thyroid tumors，and according to the new TBSRTC system，such tumors are mainly classified into follicular tumor/suspected follicular tumor，suspected malignancies，and malignancies. These tumors often have a follicular or solid structure，with or without papillary-like nuclear features，and overdiagnosis should be avoided in clinical practice.