The significance and prognostic value of multifocal papillary thyroid carcinoma in children and adolescents

Abstract Introduction The prognostic value of multifocality in paediatric papillary thyroid carcinoma (PTC) patients remains a subject of debate. This study aimed to explore the clinical significance and prognostic value of multifocality in children and adolescents with PTC. Methods This study retrospectively analysed the clinicopathological characteristics and postoperative follow-up data of 338 PTC patients aged ≤ 20 years from May 2012 to July 2022. The clinical and pathological characteristics of 205 patients with unifocal lesions and 133 patients with multifocal lesions were compared. A logistic regression model evaluated the relationship between multifocal lesions and disease recurrence/persistence in children and adolescents with PTC. Based on the median follow-up time of children with multifocal PTC, 114 patients with multifocal PTC older than 20 years were added, and the clinicopathological characteristics were compared between the 133. paediatric/adolescent patients and 114 adult patients with multifocal PTC. Results Among the paediatric and adolescent patients, over a median follow-up time of 49 months, 133 had multifocal disease and 205 had unifocal disease. Multifocal PTC patients exhibited stronger invasiveness in the form of extrathyroidal extension, tumour diameter, lymph node metastasis, and distant metastasis. Multifocality (OR 2.68; p = 0.017), lateral lymph node metastasis (OR 2.85; p = 0.036), and distant metastasis (OR 4.28; p = 0.010) were identified as independent predictive factors for the recurrence/persistence of disease. Comparing the paediatric/adolescent vs. adult multifocal patients, the former demonstrated greater tumour invasiveness. Lateral lymph node metastasis (OR 6.36; P = 0.012) and distant metastasis (OR 3.70; P = 0.027) were independent predictive factors for recurrence/persistence of disease in multifocal patients, while age was not (OR 0.95; P = 0.455). Conclusion Tumour multifocality independently predicts persistent/recurrent disease in paediatric and adolescent PTC patients.