A 35-year-old woman received a surgery of sigmoid colon highly differentiated mucosal adenocarcinoma with greater omentum and peritoneum metastasis.The follow-up contrast-enhanced computed tomography (CT) revealed a new enhanced nodule on the transverse mesocolon about 6 months after surgery. Fluorine-18-fluorodeoxyglucose (18F-FDG) and 18F-fibroblast activation protein inhibitor (FAPI) positron emission tomography (PET)/CT were both performed to evaluate the potential lesions systematically, PET/CT images showed low 18F-FDG activity but very little 18F-FAPI activity in the nodule on the transverse mesocolon. Ultimately, the nodule was pathologically proved to be sutures granuloma. Maybe 18F-FAPI PET/CT is a potential choice to differentiate suture granulomas from metastasis.