Natural History and Outcomes of Cytologically Benign Thyroid Nodules in Children.

Context: Most pediatric thyroid nodules are cytologically benign, but few data exist to guide treatment.

Objective: To describe the natural history and outcomes of cytologically benign, pediatric thyroid nodules.

Design: Cohort study.

Setting: Multidisciplinary thyroid clinic at an academic medical center.

Patients: Consecutive pediatric patients (≤18 years old) with cytologically benign thyroid nodules evaluated between 1998 and 2016.

Results: Cytologically benign nodules (N = 237) in 181 patients were followed by ultrasound (median follow-up, 3.4 years; range, 0.5 to 13.9 years) or to resection. Thyroid cancer was diagnosed in six nodules (2.5%), and all six patients were disease free after median follow-up of 4.9 years. Malignancy was more common in nodules >4 cm (15.4%; P = 0.037) or that grew during follow-up (6.0%; P = 0.048). The likelihood of nodule growth (±SE) was 15% ± 3%, 24% ± 4%, and 49% ± 10% at 6, 12, and 24 months, respectively. Among nodules >2 cm, those with ≥25% cystic content grew more slowly than nodules <25% cystic; nodules <2 cm grew similarly regardless of cystic content.

Conclusion: Benign cytology in pediatric thyroid nodules has a low false-negative rate similar to that in adults, and prognosis is excellent in the rare cases of malignancy. Resection of nodules >4 cm, combined with surveillance of smaller nodules and repeated aspiration for growth, detects most false-negative results. Follow-up ultrasound in 12 months is appropriate for most cytologically benign pediatric nodules, but delaying surveillance up to 24 months may be reasonable in large, predominantly cystic nodules.