Fine needle aspiration cytology of 650 thyroid nodules operated for multinodular goiter: a cyto-histological correlation based on the new Italian cytological classification (siapec 2014)

The new italian cytological classification (SIAPEC 2014) of thyroid nodules, in line with the Bethesda and BTA-RCPath ones, replaces the previous TIR3 class with two new classes (TIR3A and TIR3B), to which correspond different risks of malignancy and clinical actions required. The present study was conducted to evaluate the diagnostic accuracy of the new SIAPEC classification as opposed to its previous version (SIAPEC 2007). Preoperative cytology was compared with the final histology obtained from 650 consecutive patients submitted to total thyroidectomy for multinodular goiter. Of these 434 patients (group A) had their cytological diagnosis based on the old SIAPEC 2007 classification and 216 patients (group B) had their cytological diagnosis based on the SIAPEC 2014 classification. In group A 111 patients (25.6%) had a TIR3 diagnosis, while in group B 52 patients (24.1%) received a TIR3 diagnosis, of which 30 had TIR3A and 22 had TIR3B. In group A, 46 (41.4%) out of the 111 patients with TIR3 diagnosis had, based on histology, a thyroid carcinoma. In group B, only 2 (6.7%) out of 30 patients with TIR3A diagnosis had a thyroid carcinoma. This rate of malignancy was significantly lower (p<0.001) of that observed in patients with TIR3B diagnosis, in which 12 (54.5%) out of 22 patients had a carcinoma. The observations here reported show that, with respect to its previous version, the new italian cytological classification provides greater diagnostic accuracy for detecting thyroid nodule malignancy.