Renal cell carcinoma with proliferative lupus nephritis

We report a case of renal cell carcinoma diagnosed after a patient was treated successfully with intravenous cyclophosphamide for her active proliferative lupus nephritis (classes III and V). After the intravenous cyclophosphamide regimen, the patient was asymptomatic with persistent microscopic haematuria, and no proteinuria. The renal cell carcinoma was located on the left kidney; incidentally, this was where the initial renal biopsy was done to diagnose lupus nephritis.