CA9 and nonpapillary renal cell carcinoma: Despite the high specificity of [89Zr]Zr-DFO-girentuximab to visualize primary and metastatic ccRCC-lesions expressing CAIX [5, 13–15, 27] and the careful assessment of [89Zr]Zr-DFO-girentuximab PET/CT by three independent nuclear physicians with a fairly good agreement (kappa 0.71;95%CI:0.60–0.82), our results are limited by the lack of histological confirmation of the detected lesions.