OBJECTIVETo explore the ultrasound (US) findings of partially cystic thyroid nodules (PCTNs) and to analyze their relationship with differential diagnosis of benign and malignant lesions.

METHODS265 cases of PCTNs confirmed by needle biopsy or surgical pathology were included in this study. Their ultrasound characteristics were reviewed and their significance in differential diagnosis was analyzed.

RESULTSIn the 265 PTCNs, 53 cases were malignant and 212 cases were benign lesions. According to the comparison of ultrasound and pathology results, there were 51 true-positive cases, 208 true negative cases, four false-positive cases and two false negative cases;the sensitivity was 96.2% (51/53), specificity was 98.1% (208/212), positive predictive value (PPV) was 92.7% (51/55), negative predictive values (NPV) was 99.0% (208/210), and accuracy rate was 97.7% (259/265). In terms of the PTCNs, internal structure, shape and margin were significantly associated with malignant or benign nature (P < 0.001); the aspect ratio ≥ 1, spiculated or micro-lobulated margin were significantly associated with malignancy; while the smooth margin, spongiform structure were significantly associated with benign nature. In terms of the internal solid portion of the nodules, the configuration, free margin, echogenecity, and calcification were significantly associated with malignant or benign nature (P < 0.001). The eccentric configuration with an acute angle, non-smooth free margin, hypoechogenecity, marked hypoechogenecity and micro-calcification were significantly associated with malignancy; while concentric configuration, smooth free margin, hyper/isoechogenicity, free margin of the solid component, and macro-calcifications were significantly associated with benign nature (P < 0.01). The results of logistic regression analysis showed that the echogenicity, free margin, configuration and calcification of the solid component were important predictive factors of malignant lesions (P < 0.05), that the hypoechogenecity, marked hypoechogenecity, eccentric configuration with an acute angle, non-smooth free margin and micro-calcification of the internal solid portion of the nodules were predictors for malignant PTCNs (P < 0.01).

CONCLUSIONUnderstanding the characteristics of US findings of partially cystic thyroid nodules is of great importance to make an accurate diagnosis of malignant nodules.