Clinical characteristics and prognosis of histological subtypes of papillary thyroid carcinoma in pediatric patients.

Abstract

The purpose of this study was to clarify the clinicopathological features and prognosis of histological subtypes of papillary thyroid carcinoma (PTC) in the pediatric population treated at a single institution. A total of 153 PTC patients ≤18 years of age who underwent initial surgery between 1979 and 2019 were investigated. There were 135 female and 18 male patients, with a mean age at the time of surgery of 16 (range, 8-18) years. The most common subtypes included classic PTC in 124 (81%), solid variant in 16 (10%), diffuse sclerosing variant in 7 (5%) and follicular variant in six (4%) according to the 5th edition of the WHO classification. At initial surgery, 49 patients (32%) had clinical lymph node metastases (cN1), 137 patients (90%) had pathological lymph node metastases (pN1), 73 patients (48%) had number of lymph node metastases (NLNMs) ≥10, 16 (10%) had gross extrathyroidal extension (ETE) and 18 (12%) had lung metastases. During a mean follow-up of 16 years, three (2%) patients died of their disease and 34 (25%) patients had recurrent disease. The 30-year cause-specific survival rate was 97.2%, and the 30-year disease-free survival (DFS) rate was 65.0%. On multivariate analysis, gross ETE, cN1 and NLNMs ≥10 identified as significant factors related to DFS (hazard ratio (HR) 4.13, confidence interval (CI) 1.48-9.96, P = 0.009; HR 2.34, CI 1.09-4.95, P = 0.0293; HR 2.81, CI 1.30-6.59, P = 0.008), but not histological subtype, were associated with disease recurrence. Histological subtypes were not associated with disease recurrence, but long-term follow-up of pediatric patients is necessary to investigate the biological characteristics.

Synopsis: This retrospective study investigated the clinicopathological features and clinical outcomes of histological subtypes of PTC in a large series of pediatric patients treated at a single institution. It found that the prognosis of pediatric patients with PTC was excellent, but recurrence was common. In pediatric PTC, histological subtype did not affect survival and recurrence.