Keloid is a benign fibroproliferative growths resulting from an overexuberant healing response. A 51-year-old man with a 20-year history of keloid formation presented with a 1-year history of unexplained progressive weakness of both lower limbs. He was clinically suspected of having paraneoplastic neurologic syndrome. FDG PET/CT was performed to exclude underlying malignancy. FDG PET/CT revealed a giant FDG-avid keloid in the anterior chest wall without any other abnormal FDG uptake in the body. We emphasize that a benign FDG-avid keloid should be considered in the differential diagnosis of FDG-avid cutaneous lesions on PET/CT.