Figure 4. 38-year-old man with multiple thyroid nodules.

A 8-mm sized hypoechoic nodule (empty arrows) with suspicious calcifications (arrows), and spiculated margins was seen in right lower isthmus on US. US assessment was suspicious malignant. Initial US-FNA was diagnosed as atypia of undetermined significance, and negative for BRAF^V600E mutation. Follow-up US-FNA and BRAF^V600E mutation analysis was performed 6 months later, and follow-up cytology was diagnosed as benign, but positive results on BRAF^V600E mutation analysis. Surgery was performed, and this nodule was confirmed as PTC.