Characteristics of Follicular Variant Papillary Thyroid Carcinoma in a Pediatric Cohort

Context In adults, noninvasive follicular variant of papillary thyroid carcinoma (FVPTC) is considered a low risk for metastasis and persistent/recurrent disease. Objective The goal of this study was to assess the clinical, sonographic, and histopathologic features of FVPTC in a pediatric cohort. Design A retrospective review of subjects <19 years of age with papillary thyroid carcinoma (PTC) who underwent thyroidectomy between January 2010 and July 2015. Setting Multidisciplinary academic referral center. Patients Patients with FVPTC, defined as a tumor ≥1 cm in the largest dimension with predominant follicular growth, complete lack of well-formed papillae, and nuclear features of PTC. Main Outcome Measures Tumor size and location, presence of a tumor capsule, capsule and vascular invasion, lymph node invasion, and distant metastasis. Results Eighteen patients with FVPTC were identified from a case cohort of 110 patients with PTC. On histopathology, 13 (72%) had unifocal nodules and 14 (78%) had completely encapsulated FVPTC. Capsule invasion was frequent (nine of 14; 64%), and vascular invasion was found in one-third of patients (six of 18; 33%). No lymph node metastases were found in the 13 patients (72%) who had a central neck lymph node dissection. One patient with vascular invasion had distant metastases. Conclusion When strictly defined, FVPTC in pediatric patients has a low risk for bilateral disease and metastasis. Prospective studies are needed to confirm whether lobectomy with surveillance is sufficient to achieve remission in pediatric patients with low-risk FVPTC.