“Metabolic signature” of the lesions on F18-fluoro-deoxyglucose positron emission tomography: A clue to the underlying pathology

Increase in glycolytic pathway, forms one of the major adaptations in various cancer types. This can be imaged using (18)F-fluoro-deoxyglucose positron emission tomography/computed tomography (FDG PET). The intensity of FDG avidity is an indirect marker of the grade of the tumor. We present a case where FDG PET demonstrated a known chondrosarcoma and two other incidental lesions. The intensity of avidity in each of the lesions was grossly incongruent from the chondrosarcoma and further investigation proved the lesions to be two distinct primary malignancies, pathologically different from the known chondrosarcoma. We present the case to highlight the fact that the grade of FDG avidity is a clue to the pathological nature of the lesion and should always be considered while interpreting PET images.