Predictive factors of malignancy in patients with cytologically suspicious for Hurthle cell neoplasm of thyroid nodules

Abstract

Background: Our aim was to evaluate predictive factors of malignancy in patients with cytologically suspicious for Hurthle cell neoplasm (HCN) of thyroid nodules.

Materials and methods: We searched cases with cytologically suspicious for HCN from 11,569 ultrasound-guided fine-needle aspirations (US-FNA) performed at our institution. Nodules that were confirmed surgically or followed-up for at least 2 years were compared with respect to age, gender, tumor size, US diagnosis, and US findings to predict malignancy.

Results: The incidence of cases with cytologically suspicious for HCN was 1.2% (143 of 11,569). Of 75 nodules that underwent sufficient follow-up or surgery, malignancies were found in 11 (14.7%). Malignant histological examination revealed oncocytic variants of papillary thyroid carcinoma (PTC) in 3 cases, classic PTC in 1, Hurthle cell carcinoma in 3, follicular carcinoma in 3 and an unclassified carcinoma in 1. In univariate analysis, tumor size was significantly larger in malignant nodules compared to benign nodules (p = 0.026). The best cut-off value of tumor size in predicting malignancy was 2.5 cm. (p = 0.006, sensitivity: 63.6%, specificity: 79.7%). The incidences of hypoechogenicity and malignant US diagnoses were higher in malignant nodules than in benign nodules (p < 0.001). In multivariate analysis, tumor size was an independent factor in predicting malignancies. (p = 0.037, odd ratio: 2.09, confidence interval: 1.046-4.161).

Conclusion: Preoperative US provides predictive factors of malignancy in thyroid nodules with cytologically suspicious for HCN. Predictive factors include tumor size of 2.5 cm or greater, hypoechoic nodule and malignant US diagnosis.

Keywords: Diagnosis; Hurthle cell neoplasm; Predictive factor; Thyroid nodule; Ultrasonography.