[Clinicopathological and molecular characteristics of pediatric and adolescent papillary thyroid carcinoma]

Objective: To investigate the clinicopathological and molecular characteristics, treatment modalities, and prognosis of papillary thyroid carcinoma (PTC) in children and adolescents. Methods: A retrospective analysis was conducted on the clinicopathological data of children and adolescents diagnosed with PTC at Gansu Provincial Cancer Hospital from February 2022 to August 2025. Multigene mutation/fusion testing was performed using fluorescence polymerase chain reaction (PCR), and NTRK1/3 rearrangements were detected by fluorescence in situ hybridization. Results: A total of 21 patients (15 females, 6 males; age range, 4-18 years) were enrolled, of whom 5 had a history of childhood radiation exposure. Histological subtypes included classic (n=13), follicular (n=4), diffuse sclerosing (n=3), and solid/trabecular (n=1). Molecular profiling revealed BRAFV600E mutation in 7 cases, NTRK fusion in 2 cases, NCOA4::RET fusion in 2 cases, and CCDC6::RET fusion in 2 cases. Both NTRK fusion cases harbored NTRK3 rearrangement and were of the follicular subtype. RET fusion cases exhibited a higher propensity for vascular tumor thrombus and psammoma body formation. During a follow-up period of 3 to 45 months, lymph node metastasis occurred in 18 patients and pulmonary metastasis in 4 patients. Conclusion: Among children and adolescents with PTC, female predominance is observed, with classic PTC being the most common histological type. NTRK and RET fusion genes occur with higher frequency in this population. Treatment should integrate radical intent with individualized strategies, and prognostic evaluation requires comprehensive integration of both clinical and molecular parameters.