The purpose of this Expanded Access Program (EAP) is to enable the use of 89Zr-DFO-girentuximab with positron emission tomography/computed tomography (PET/CT) imaging to non-invasively detect carbonic anhydrase 9 (CAIX)-expressing clear cell renal cell carcinoma (ccRCC) in patients with renal masses as determined by conventional imaging.

Inclusion Criteria:

1. Written and voluntarily given informed consent.
2. Male or female ≥ 18 years of age.
3. Imaging evidence of renal mass(es) obtained from conventional diagnostic imaging with CT or MRI (without and with contrast enhancement) based on national standards that is not older than 90 days on Day 0, and that was performed before any screening procedure.
4. Negative urine/serum pregnancy tests in female patients of childbearing potential.
5. Consent to practice highly effective contraception until a minimum of 42 days after IV 89Zr-DFO-girentuximab administration.

Exclusion Criteria:

1. Renal mass known to be a metastasis of another primary tumor.
2. Active non-renal malignancy requiring therapy during and up to EOT visit.
3. Radiotherapy or immunotherapy within 4 weeks (28 days) prior to the planned administration of 89Zr-DFO-girentuximab or continuing adverse effects (> grade 1 using Common Terminology Criteria for Adverse Events [CTCAE] version 5.0) from such therapy.
4. Planned antineoplastic therapies (for the period between IV administration of 89Zr-DFO-girentuximab and imaging).
5. Previous administration of any radionuclide within 10 of its half-lives before Day 0.
6. Serious non-malignant disease (e.g., psychiatric, infectious, autoimmune, or metabolic), that may interfere with the objectives of the program or with the safety or compliance of the subject, as judged by the Investigator.
7. Mental impairment that may compromise the ability to give informed consent and comply with the requirements of the program.
8. Exposure to any experimental diagnostic or therapeutic drug within 30 days from the date of planned administration of 89Zr-DFO-girentuximab.
9. Women who are pregnant or breastfeeding.
10. Known hypersensitivity to girentuximab or DFO (desferoxamine).