Granulation tissue: Pitfall in therapy control with F-18-FDG-PET after chemotherapy

False positive findings in primary tumor and metastasis diagnostics by FDG- PET due to FDG-uptake in inflammatory foci are documented in literature. Th e demonstrated case reveals that increased uptake of FDG in activated neutr ophile granulocytes and macrophages has to be taken into consideration in t herapy control under chemotherapy, too. In a 53 year old patient FDG-PET wa s performed after chemotherapy of an abdominal Non-Hodgkin lymphoma for eva luation of persistent tumor vitality. The margin of the persisting mass sho wed increased uptake of glucose. Histology documented a necrotic center sur rounded by granulation tissue.