Clinical significance of multimodal ultrasound features in predicting cervical lymph node metastasis in papillary thyroid carcinoma with cystic change.

Background: Papillary thyroid carcinoma (PTC) with cystic change is a relatively rare imaging phenotype, and its risk factors for cervical lymph node metastasis (CLNM) remain insufficiently investigated. This study aimed to identify independent CLNM predictors using multimodal ultrasound features and to evaluate their predictive performance. Methods: We retrospectively enrolled 185 patients with pathologically confirmed PTC with cystic change who underwent preoperative conventional ultrasound, shear-wave elastography (SWE), and contrast-enhanced ultrasound (CEUS) followed by surgical resection. The patients were divided into the CLNM group (n=127, 68.6%) and non‑CLNM group (n=58, 31.4%) based on postoperative pathology. Clinical data and ultrasound parameters [nodule size, calcification, Adler blood flow grade, capsular invasion, SWE elasticity ratio (Eratio), and CEUS enhancement intensity] were compared. Multivariate logistic regression was used to identify independent predictors, and model discrimination was assessed by receiver operating characteristic (ROC) curve analysis. Results: The univariate analysis showed that the patients in the CLNM group were significantly younger (median age 34.0 Conclusions: In PTC with cystic change, younger age, larger nodule diameter, calcification (especially microcalcification), and capsular invasion were found to be independently associated with CLNM. A prediction model based on these readily available preoperative features showed good diagnostic performance [area under the curve (AUC) 0.818] and may facilitate individualized surgical decision-making.