Fig. 1. Examples of core needle biopsy (CNB) in thyroid nodules with initial non-diagnostic fine-needle aspiration cytology. (A) On the ultrasound findings of case 1, there is a well-defined hypoechoic solid nodule with rim calcification. (B) CNB of the nodule shows scanty cellular and sclerotic nodules (H&E stain, ×40). (C) A high-power view shows the typical histologic features of papillary carcinoma (H&E stain, ×1,000). (D) An ultrasound image from case 2 shows a 1.5-cm, ill-defined hypoechoic solid nodule with macrocalcifications. (E) CNB shows marked calcification sclerosis, and focally follicular proliferative lesions (H&E stain, ×40). (F) A high-power view of the follicular lesion shows the histologic findings of papillary carcinoma (H&E stain, ×1,000).