68 Ga-FAPI-04 Outperforms 18 F-FDG in Detecting Lesions for Primary Leiomyosarcoma of Bone : A Rare Case.

Primary leiomyosarcoma of bone (PLB) is an ultrarare tumor, characterized by its aggressive clinical behavior, high heterogeneity, and dismal prognosis. Here, we present the 68 Ga-FAPI-04 and 18 F-FDG PET/CT findings in a case of PLB affecting the left femur. FAPI PET/CT showed more bone lesions and higher uptake in the multiple metastatic lesions compared with FDG PET/CT. More interestingly, FAPI PET/CT could clearly detect the tumor embolus on the left common femoral artery, which was negative on FDG. This case suggests that FAPI PET/CT is a promising method for the primary diagnosis and staging of PLB.