To establish a nomogram for predicting large-number cervical lymph node metastases (LNMs) of primary papillary thyroid carcinoma (PTC) based on ultrasound characteristics. This retrospective study included patients with PTC diagnosed by pathological examination and who underwent surgery between August 2015 and May 2021 at Hwa Mei Hospital, University of Chinese Academy of Sciences (Ningbo, China). Large-number LNM was defined as >5 lymph nodes with metastases. The patients were propensity score-matched (PSM) for age and sex. A multivariable analysis was used to determine the risk factors for massive LNM. After PSM, the 78 patients with large-number LNM were matched with 312 patients with small-number LNM. Compared with the patients with small-number LNM, those with large-number LNM had larger tumors (13.0 ± 7.7 vs. 6.8 ± 3.8 mm, p < 0.001), and higher frequencies of multifocal nodules (42.3% vs. 22.4%, p < 0.001), taller-than-wide shape (82.1% vs. 56.7%, p < 0.001), calcifications (76.9% vs. 47.4%, p < 0.001), microcalcifications (68.0% vs. 36.5%, p < 0.001), capsule invasion (32.1% vs. 17.6%, p = 0.005), and ultrasound diagnosis of LNM (44.9% vs. 9.3%, p < 0.001). The multivariable analysis showed that nodule size (OR = 1.19, 95%CI: 1.11-1.27, p < 0.001), multifocal disease (OR = 2.50, 95%CI: 1.30-4.80, p = 0.006), taller-than-wide shape (OR = 0.45, 95%CI: 0.22-0.93, p = 0.032), and ultrasound diagnosis of LNM (OR = 5.57, 95%CI: 2.73-11.37, p < 0.001) were independently associated with large-number LNM. A nomogram was built, and the area under the receiver operating characteristics curve was 0.86 (95%CI: 0.81-0.90). A nomogram was successfully built to predict large-number LNM in patients with PTC, based on nodule size, multifocality, taller-than-wide shape, and ultrasound diagnosis of LNM.
Keywords: Nomograms; Papillary thyroid carcinoma; Ultrasound.