FDG-PET EVALUATION OF RETROPERITONEAL METASTASES OF TESTICULAR CANCERBEFORE AND AFTER CHEMOTHERAPY

We describe a patient whose primary tumor was a testicular teratocarci noma predominantly composed of embryonal carcinoma. Before chemotherap y, the retroperitoneal metastases demonstrated heterogeneous, increase d glucose metabolism as measured by 2-[F-18]fluoro-2-deoxy-D-glucose a nd PET(FDG-PET). After chemotherapy, FDG uptake was reduced to normal Values despite increased tumor volume. Histology revealed a pure matur e teratoma. This observation suggests that further studies are needed to determine whether tumor differentiation of testicular teratocarcino ma metastases can be assessed by measuring glucose metabolism.