Sonographically Suspicious Thyroid Nodules with Initially Benign Cytologic Results: The Role of a Core Needle Biopsy

Purpose: To evaluate the diagnostic role of core needle biopsy (CNB) in sonographically suspicious thyroid nodules with initially benign cytologic results through a histologic analysis of CNB specimens. Methods: Between October 2008 and July 2011, 88 patients underwent ultrasound (US)-guided CNB for initially benign cytologic results with suspicious US features at our institution. In all, 85 patients with 85 focal thyroid nodules were included in the study after surgery or concordant benign readings following fine-needle aspiration biopsy (FNAB) and CNB. We evaluated the risk of malignancy, diagnostic performance of CNB, and histologic findings for these nodules. Results: Of the 85 nodules, 28 (32.9%) were histologically upgraded on CNB specimens including one case of atypia of undetermined significance (AUS), seven cases of follicular neoplasm, one case of suspicious for malignancy, and 19 cases of malignancy. Of these, 27 (31.8%) were finally confirmed as malignant, and one as follicular adenoma at surgery. The 27 malignant nodules included 21 papillary thyroid carcinomas (PTCs), five follicular thyroid carcinomas, and one Hurthle cell carcinoma. All PTCs were diagnosed from CNB readings of AUS suspicious for malignancy or malignancy. Follicular thyroid carcinomas and Hurthle cell carcinoma were diagnosed from CNB readings of follicular neoplasm. Histologic analysis of benign CNB specimens revealed severe fibrosis (96.4%), hemosiderin (21.4%), calcification (17.9%), granulation tissue (12.5%), and focal lymphocytic thyroiditis (12.5%). Conclusions: The histologic information obtained by analysis of CNB specimens may enable more confident diagnosis for benign nodules with suspicious US features and reduce the need for repetitive FNABs or diagnostic surgery.