We experienced a case of the papillary thyroid carcinoma seen as a huge solid lateral neck mass. The mass grew very slowly over the period of 30years up to 10cm in diameter while relatively well sparing the surrounding tissues. Physical examinations, CT scan, and fine needle aspiration cytology did not reveal any strong suggestions for evidence of malignancy. But it was pathologically diagnosed as metastatic thyroid carcinoma by excisional biopsy. We emphasize that for a large solitary neck mass which persists for several decades, head and neck surgeons should always keep in mind the possibility of metastasis from the malignancy of thyroid gland.