The rate of malignancy in the follicular neoplasm (FN) or Hürthle cell neoplasm (HCN) of the thyroid gland is estimated as approximately 20~30%. Fine-needle aspiration biopsy (FNAB) and frozen section examination are restricted in differentiating between benign and malignant. The aims of this study are to compare the differences of clinicopathologic features and to determine the risk factors for malignancy in patients with FN or HCN.

A retrospective study was conducted of patients with FN or HCN who were diagnosed by FNAB, and underwent surgery at our institution between Jan. 2005 to Jun. 2010. We analyzed the risk factors for malignancy and the differences of clinicopathologic features in patients with FN or HCN.

A total of 290 patients were enrolledin this study; 160 (55.2%) patients underwent thyroidectomy, 97 (60.6%) patients had FN, and 63 (39.4%) had HCN. Forty one (25.6%) patients were diagnosed as malignancy of these, 22 (22.7%) patients were FN and 19 (30.2%) were HCN (P=0.29). Two (2.1%) patients with FN and 10 (15.9%) with HCN (P=0.002) comcomitant papillary thyroid carcinoma were indentified by FNAB. Classification of nodules according to ultrasonographic findings in both neoplasms (P<0.05) and galectin-3 in FN (P<0.05) were predictive factors for malignancy. In addition, galectin-3 was a predictive factor for malignancy in indeterminate nodules on ultrasonography (USG) (P=0.028).

Classification of nodules according to ultrasonographic findings and galectin-3 expression is helpful in predicting carcinoma of patients with FN or HCN.