Differences in Thyroid Nodule Cytology and Malignancy Risk Between Children and Adults

Area of Science:

• Endocrinology
• Pathology
• Pediatric Oncology

Background:

• The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) guides thyroid nodule management based on malignancy risk derived from adult data.
• The applicability of adult-derived malignancy risk stratification to pediatric thyroid nodules is uncertain.

Purpose of the Study:

• To compare malignancy rates between pediatric and adult thyroid nodules across BSRTC cytological categories.
• To determine if current BSRTC risk stratification is appropriate for pediatric thyroid nodule management.

Main Methods:

• Retrospective analysis of consecutive thyroid nodules (≥1 cm) from pediatric (<19 years) and adult (≥19 years) patients undergoing fine-needle aspiration (FNA) from 1998 to 2016.
• Cytology interpreted using BSRTC by a single cytopathology group.
• Comparison of malignancy rates between pediatric and adult cohorts within each cytological category.

Main Results:

• Pediatric nodules had a higher overall malignancy rate (19% vs. 12%, p=0.0002).
• Significantly higher malignancy rates were observed in pediatric nodules within the nondiagnostic (11% vs. 4%), atypia of undetermined significance (AUS; 44% vs. 22%), and suspicious for follicular neoplasm (SFN; 71% vs. 28%) categories.
• Malignancy rates for benign, suspicious for papillary carcinoma, and positive for malignancy categories showed no significant differences between pediatric and adult groups.

Conclusions:

• Pediatric thyroid nodules, especially those classified as nondiagnostic, AUS, or SFN, exhibit higher malignancy rates compared to adult nodules.
• These discrepancies highlight potential differences in intrinsic malignancy risk between pediatric and adult populations.
• Findings support the need for pediatric-specific data to optimize the management of thyroid nodules in children, potentially differing from adult protocols.