Fig 3.
A PCTN in the right lobe of a 75-year-old man was classified as benign by thyroid US (false-negative). A and B, Transverse and longitudinal gray-scale US images show typical benign US features for the nodule, except for a small-sized hypoechoic solid component (arrow) within the nodule (approximately 1.5 × 2.0 × 2.6 cm3). In the initial US-FNA, the isoechoic and hypoechoic solid components of the PCTN were simultaneously sampled, and the nodule showed indeterminate cytology (atypia of undetermined significance). In repeat US-FNA, the small hypoechoic solid component of the nodule (arrow) was the focus of the sampling, and the cytologic result was suspicious for malignancy (Bethesda class V). After thyroid surgery, the nodule was confirmed to be a papillary thyroid microcarcinoma (follicular variant) that arose from nodular hyperplasia.