An 18-year-old male complained of "the discovery of a submental mass for more than 4 months". Physical examination: A tough mass about 4 cm in diameter under the chin, with a clear boundary, can be pushed. Both thyroid glands were palpable with 1 cm diameter masses, which were hard, fixed and unclear. The enlarged lymph nodes were not palpable. Laboratory tests showed that serum T3, T4, FT3, FT4, TSH, TPO-Ab and Tg-Ab were normal. Ultrasound: Bilateral thyroid nodules (TI-RADS4c), multiple enlarged lymph nodes and submental cystic-solid mass were seen in areas III, IV and VI of the left cervix and IV and VI of the right cervix. Total thyroidectomy + prehyoid mass resection + thyroglossal duct resection + partial hyoid resection + bilateral lymph node dissection in zone Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅵ were performed (Figure 1), postoperative pathological report: bilateral papillary thyroid carcinoma without vascular tumor thrombus and nerve invasion, involving thyroid envelope; Papillary thyroid carcinoma can be seen in the prehyoid mass. Metastatic carcinoma was seen in lymph nodes (19/81). Mutation of the BRAF V600E gene in the prehyoid mass. Postoperative line131I treatment and TSH inhibition, no recurrence and metastasis were observed after 15 months follow-up.