Ultrasonographic Features of Benign Nodules, Follicular Lesions and Malignant Nodules in the Thyroid Diagnosed Mainly by Fine Needle Aspiration Biopsy

The purpose of this study was to compare the ultrasonographic features of benign nodules, follicular lesions and malignant nodules in the thyroids of patients who underwent fineneedle aspiration biopsy. We retrospectively analyzed the ultrasonographic features of 231 nodules, which were diagnosed as benign, follicular lesion or malignant nodules with respect to solitariness, echogenicity, echostructure, border characteristics, presence or absence of calcifications, internal vascularity and the presence of a halo. The ultrasono-graphic features of benign nodules, follicular lesions and malignant nodules were compared using the Fisher-Freeman-Halton exact test. Differences were statistically significant if p < 0.05. With regard to cytopathology, there were 186 benign nodules, 10 follicular lesions and 35 malignant nodules. The distribution of frequencies of the ultrasonographic features including hypoechogenicity [46/186 (24.7%), 4/10 (40%), 29/35 (82.9%)], solid echostructure [63/186 (33.9%), 7/10 (70%), 34/35 (97.2%)], irregular margin [29/186 (15.6%), 3/10 (30%), 27/35 (77.1%)], microcalcification [16/186 (8.6%), 2/10 (20%), 15/35 (42.9%)] and absence of a halo [55/186 (29.5%), 5/10 (50%), 33/35 (94.2%)] between benign nodules, follicular lesions and malignant nodules, respectively, was statistically significant (Fisher-Freeman-Halton, p < 0.05). The frequencies of solitariness [35/186 (18.8%), 2/10 (20%), 7/35 (20%)] and internal vascularity [101/186 (54.3%), 7/10 (70%), 21/35 (60%)] between benign nodules, follicular lesions and malignant nodules, respectively, were not statistically significant (p > 0.05). Ultrasound features including hypoechogenicity, solid echostructure, irregular margin, presence of microcalcification and absence of a halo might be effective in the differentiation of malignant nodules and follicular lesions from benign nodules.