Risk factors of lymph node metastasis in the diffuse sclerosing variant of papillary thyroid carcinoma compared with conventional papillary thyroid carcinoma in pediatric populations

Objective: To analyze the clinicopathological features and predictors of lymph node metastasis (LNM) in the diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) and compare these findings with conventional papillary thyroid carcinoma (C-PTC) in pediatric populations. Methods: Patients aged 18 years or younger who were preoperatively diagnosed with PTC and underwent thyroidectomy at the First Affiliated Hospitals of Nanchang University from January 2017 to May 2024 were included in this study. Demographic and clinicopathological characteristics were retrospectively analyzed. Univariate and multivariate analyses were performed to identify risk factors for lymph node metastasis. Clinical outcomes, including nerve injury, hypocalcemia, and recurrence, were also recorded and evaluated. Results: A total of 119 children were enrolled in this study, with a median age of 15.6 years. Of these, 89 (74.8 %) were female, and 18 (15.1 %) were diagnosed with DSV-PTC. Central lymph node metastasis (CLNM) was observed in 94 (79 %) patients, while 60 (50.4 %) had lateral lymph node metastasis (LLNM). DSV-PTC was associated with a higher incidence of CLNM and LLNM compared to C-PTC (p = 0.039, p < 0.001). Multifocality and bilateral tumors were also more common in DSV-PTC (p < 0.001). Cox regression analysis identified tumor size as an independent predictive factor for CLNM in pediatric C-PTC patients. Tumor size, ETE and the presence of CLNM were independent predictive factors for LLNM. After a mean follow-up of 32.8 months, no patient died from the disease, but four C-PTC patients (4.0 %) developed local recurrences, which were managed surgically. Lung metastasis occurred in 2 (11.1 %) DSV-PTC and 1(1.0 %)C-PTC patients, respectively. Permanent injuries included one case of unilateral recurrent laryngeal nerve(RLN) injury and two cases of bilateral RLN injury. Four patients (4.0 %) experienced temporary hypocalcemia, which resolved after 6 months of calcium therapy. Conclusions: DSV-PTC presents unique characteristics of lymph node metastasis and may be more aggressive than conventional PTC in pediatric populations. The presence of CLNM, tumor size and ETE were identified as independent predictors of LLNM in pediatric patients with conventional PTC. Evaluating these prognostic factors may help in customizing individualized surgical approaches for children, thereby reducing unnecessary surgical complications.