Two women presented with abdominal complaints; after clinical investigation and ultrasonography, both were suspected of having (ovarian) teratoma. The CT scan showed enlarged para-aortic lymph nodes, which increased the suspicion of a malignant process. Total-body 18F-FDG PET/CT studies helped to differentiate benign from malignant ovarian teratoma, as well as abdominal lymphadenopathy, subsequently confirmed by histopathology. When there is suspicion of a malignant teratoma, 18F-FDG PET/CT may help in accurate diagnosis and staging; as for malignant disease (either malignant transformation of mature cystic teratoma or malignant immature teratoma), a more aggressive, multimodality approach may be indicated.