High-Risk Histological Subtypes of Papillary Thyroid Carcinoma Predict More Aggressive Disease in Pediatric Patients

Papillary thyroid carcinoma (PTC) is uncommon in children compared with adults. Studies have examined the significance of histologic subtype on outcomes in adults; less is known about its importance in pediatric PTC. We sought to examine the relationship between PTC histologic subtype and clinicopathologic factors in children.

The LIS was queried for pediatric PTC thyroidectomy patients between 01/2000 and 12/2023. H&E slides were assessed by 2 pathologists for PTC histologic subtypes per the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. All patterns identified in each tumor were recorded. Relevant clinicopathologic data was collected and correlated with histology using 2-tailed heteroscedastic Student-t-tests.

Forty-six pediatric PTC patients were identified during the study timeframe. 16 (34.8%) tumors showed at least focal high-risk subtype morphology. The presence of any high-risk histology in any quantity correlated with higher AJCC pT stage (P = .0471), high ATA Risk Classification (P = .049), disease recurrence (P = .0357), and distant metastatic disease (P = .0034).

Our findings suggest that WHO-defined high-risk PTC histologic subtypes correlate with more aggressive disease in children. This correlation - observed regardless of the amount of high-risk subtype in a given tumor - suggests that these morphologic patterns may provide important prognostic insight for these children.