Thyroid cancer is a rare disease in pediatric population, but its incidence rate is increasing. The aim of this report is to present a single institution experience of pediatric thyroid cancer and to identify clinical features, predisposing factors, and postoperative course of pediatric thyroid cancer.

We retrospectively reviewed 35 pediatric patients who underwent operation due to thyroid cancer at Seoul National University Children's Hospital between May 1997 and January 2017. The median follow-up period was 70 months (range, 5–238 months).

The mean age at operation was 12.0±5.91 years and 27 patients were female. The underlying conditions in patients included history of chemoradiotherapy for previous other malignancies (n=4), hypothyroidism (n=3), history of chemotherapy (n=2), family history of thyroid cancer (n=1) and history of radiation therapy (n=1). The initial symptoms were palpable neck mass (n=21) and incidental findings (n=11). Total thyroidectomy (n=30) or unilateral lobectomy (n=5) were performed. There were 15 postoperative complications including transient hypocalcemia in 14 patients and Horner's syndrome in 1 patient. The most common pathologic cell type was papillary thyroid cancer (n=29). Extrathyroid extension and lymph node invasion were found in 25 patients and 27 patients, respectively. Thirteen patients showed multifocality. During follow-up period, 5 patients underwent additional operation because of tumor recurrence in lymph nodes. Lung metastasis was detected in 3 patients at the time of diagnosis and in 3 patients during follow-up period. The mortality rate was zero and mean disease-free survival was 83.7±47.9 months.

Pediatric thyroid cancer has lower mortality rate and recurrence rate as seen in this study despite the advanced stage at diagnosis. A thorough follow-up of patients with an underlying condition such as history of chemoradiotherapy and understanding new pediatric guideline can be helpful to maximize patients' survival and prognosis.