Increased FDG activity in a dermatofibroma in esophageal cancer patient.

PET using the radiotracer (18)F-FDG is used for staging patients with esophageal cancer. Nonmalignant conditions, mainly inflammation and some benign tumors, however, can cloud the clinical picture by taking up FDG and producing a false-positive result. We report the case of a 46 year-old man with squamous cell carcinoma of the thoracic esophagus who underwent combined PET/CT and had false-positive uptake in a chest wall dermatofibroma. Dermatofibroma is a benign skin lesion with a characteristic large presence of fibroblasts and macrophages. Macrophage uptake of FDG is likely responsible for the false-positive result on PET/CT.