Background Unfortunately, the cytology finding of follicular neoplasm does not distinguish between a thyroid adenoma and a carcinoma. The objective of this retrospective study was to identify the pathologic features that characterize patients with an increased risk of having a thyroid carcinoma.
Methods A total of 416 patients with follicular neoplasm who underwent thyroidectomy were reviewed at Seoul ST. Mary’s Hospital (Seoul, Korea) from January 2010 to June 2018. Clinicopatholgic features were analyzed retrospectively by complete medical chart review and pathologic slide review.
Results Thyroid malignancy was diagnosed in 209 patients (50.2%). 118 patients (28.4%) were diagnosed with follicular variant papillary thyroid carcinoma (fvPTC), 59 patients (14.2%) were diagnosed with follicular thyroid carcinoma (FTC), and 23 patients (5.5%) were diagnosed with conventional PTC. The number of patients with nuclear atypia was quite more in malignancy group than in benign group (16.4% vs. 1.9%, p<0.001). Multivariate analysis indicated that the significant risk factors of diagnosis of malignancy include cytological diagnosis with nuclear atypia (odds ratio [OR]: 10.762, 95% confidence interval [CI]: 3.002-38.575, p<0.001), NRAS mutation positive (OR: 2.483, 95% CI: 1.212-5.086, p=0.013), and male gender (OR: 2.027, 95% CI: 1.042-3.944, p=0.037).
Conclusion In our result, prevalence of carcinoma in patient with preoperative diagnosis of follicular neoplasm was much higher than previous reports. Cytological result with atypia is useful predictors for the presence of malignancy. Further studies must be conducted to support our results.