Importance The presence of extranodal extension (ENE) in metastatic papillary thyroid carcinoma (PTC) has emerged as an important prognostic factor, independently associated with tumor persistence after initial resection, decreased likelihood of complete biochemical response, and worse cause-specific survival. Therefore, the ability to determine ENE before surgery is desirable and advantageous but to date has not yet been evaluated. OBJECTIVE To evaluate the use of preoperative ultrasound characteristics in predicting pathologic ENE in patients with metastatic PTC. DESIGN, SETTING, AND PARTICIPANTS Single-institutional, retrospective analysis of patients with metastatic PTC between December 1, 2007, and May 31, 2012. The dates of the analysis were September 1, 2014, to July 31, 2015. Clinicodemographic and histopathologic data were extracted. Preoperative ultrasound images were scored for characteristics of interest by 2 independent radiologists masked to radiology and pathology reports. The setting was an academic tertiary care center. Patients were excluded if they were younger than 18 years, did not have clinical or imaging follow-up after surgery, were found to have histologic diagnoses other than PTC, or were being treated for recurrent disease. EXPOSURES Preoperative ultrasound and neck dissection. MAIN OUTCOMES AND MEASURES Association of ultrasound characteristics with ENE. RESULTS Data from 29 patients with metastatic PTC and available preoperative ultrasound images and pathologic data from neck dissection were included. The patients had a median age at diagnosis of 47 years (age range, 19-85 years); and 76%(22 of 29) were female. Among 29 patients, 11 (38%) had ENE. There were no significant differences in distributions of clinicodemographic or histopathologic characteristics between patients with vs without ENE. The following ultrasound characteristics were significantly associated with ENE positivity: node matting (odds ratio [OR], 6.67; 95%CI, 1.01-44.10; P =.049), presence of node matting or cystic areas (OR, 11.70; 95%CI, 1.85-74.19; P =.009), composite score of 3 or more ultrasound characteristics (OR, 14.00; 95%CI, 2.06-95.09; P =.007), and presence of node matting, perinodal edema, unclear margins, or cystic areas (OR, 10.00; 95%CI, 1.05-95.24; P =.045), as well as presence of node matting, perinodal edema, or unclear margins (OR, 7.07; 95%CI, 1.17-42.85; P =.03). A composite score of 3 or more ultrasound characteristics had the highest accuracy (79.3%) for predicting ENE positivity. CONCLUSIONS AND RELEVANCE This study identifies preoperative ultrasound characteristics of metastatic PTC that are significantly associated with pathologically determined ENE and supports prospective analyses to further evaluate this use of preoperative ultrasound.
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