Although high resolution ultrasonography (US) is helpful in the differentiation of suture granulomas from recurrent thyroid cancer in most cases, a definite diagnosis cannot always be made. We report a case that mimicked recurrent thyroid cancer on US and 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), but diagnosis of a suture granuloma was confirmed by a US-guided fine needle aspiration biopsy (FNAB). In order to avoid unnecessary operations, the differential diagnosis between postoperative suture granulomas and recurrent cancer is important.