Suture granuloma showing false-positive finding on PET/CT after head and neck cancer surgery

We report herein two cases of suture granuloma showing focal intense 2-deoxy-2-[18F]fluoro-d-glucose (FDG)-uptake in positron emission tomography (PET). Follow-up FDG-PET after surgical intervention for head and neck cancer revealed lesions with high FDG-uptake, which were highly suspected of being a recurrent tumor. The lesions were subjected to excisional biopsy for definitive diagnosis. Histopathological examination proved them to be suture granulomas caused by non-absorbable silk sutures. It should be emphasized that suture granulomas can show false-positive findings on FDG-PET, thus requiring differential diagnosis from recurrent tumors.