Differentiated thyroid carcinoma in children: A retrospective analysis of 125 pediatric cases from a single institution in India

Background Thyroid carcinoma (TC) is extremely rare in children. We assessed the clinicopathological features, outcomes, recurrence pattern, and associated risk factors of differentiated thyroid carcinoma (DTC). Methods Children aged <= 14 years, pathologically diagnosed as DTC at a tertiary cancer institute between January 1998 and December 2015 were retrospectively analyzed. Survival outcomes were estimated using the Kaplan-Meier method. Results During 18 years, 125 children with DTC were treated with a male:female ratio of 1:2.3. The median age was 12 years (2-14 years). Anterior neck swelling was the commonest presentation (72.8%). Histopathology revealed papillary thyroid carcinoma (PTC) in 123 children (98.4%). Extrathyroidal extension was seen in 32 children (25.6%). Sixty-eight children (54.4%) had nodal metastases and seven had distant metastasis. Relapse developed in 12 children. All were salvaged with subsequent surgery and radioiodine therapy. Eight children had persistent disease and one had a second malignant neoplasm. The median follow-up period was 9 years 1 month (1-20 years). Five-year recurrence-free survival (RFS) was 94.8% and 5-year overall survival was 100%. Larger tumors (p-value = .001), extrathyroidal extension (p-value = .001), and nodal metastasis (p-value = .022) were significant predictors for RFS in univariate analysis. Conclusions Pediatric DTC showed aggressive behavior characterized by a high rate of extrathyroidal extension and nodal and pulmonary metastasis. Persistent disease should be distinguished from recurrent disease as DTCs with metastatic disease remain stable for long time and usually respond well to radioiodine therapy. Our study reaffirmed favorable prognosis despite aggressive presentation and even after relapse.