Metastatic renal cell carcinoma without evidence of a primary renal tumour

Although metastases are common in patients with renal cell carcinoma (rcc), it is extremely rare for patients to present with metastatic rcc (mrcc) without evidence of a primary mass in the kidney. Two cases of mrcc with no detectable primary renal mass are reported here. Both patients had bilateral native kidneys in situ and no significant prior urologic history. The first patient presented with a hip fracture and was found to have multiple radiologic bony and lung metastases. Biopsy of a mass involving the pubic bone demonstrated clear cell mrcc. Multiple scans by computed tomography (ct) and confirmatory imaging by magnetic resonance demonstrated no renal mass. This first patient had disease stabilization for 18 months on sunitinib and was still alive at last follow-up. The second patient was diagnosed with clear-cell mrcc after thickened synovium was discovered and biopsied during a knee arthroplasty. Multiple scans by ct in this second patient demonstrated no primary renal mass. Sunitinib and radiotherapy to the knee lesion were initiated, but unfortunately, the patient deteriorated clinically and passed away from disease progression shortly after diagnosis. Because of the rare nature of these cases, a standardized course of action has not yet been established. However, we hypothesize that it is reasonable to manage metastases in these patients by following established mrcc protocols.