Vandetanib in a child affected by neurofibromatosis type 1 and medullary thyroid carcinoma with both NF1 and homozygous RET proto-oncogen germ-line mutations.

Cases of neurofibromatosis type 1 (NF1)-associated medullary thyroid carcinoma (MTC) or C-cell hyperplasia are rarely associated with other endocrine tumors or cases with a multiple endocrine neoplasia type 2 (MEN2). In these patients, mutations were detected in the NF1 gene but no mutations were detected in the RET gene. Although vandetanib has been shown to improve progression-free survival in adults with advanced MTC, data in pediatric patients are limited. Herein, we report the use and outcome of vandetanib in a pediatric MTC case in which NF1 gene and RET proto-oncogen mutation were identified together.