Ipsilateral synchronous neoplasms of kidney presenting as acute pyelonephritis and bladder metastasis.

Ipsilateral multiple synchronous primary renal neoplasms is an uncommon presentation, and only a few cases have been reported in published studies. We report the case of a 57-year-old woman with acute pyelonephritis as the initial presentation, in whom conservative treatment had no effect. Surgical intervention revealed the presence of concomitant renal cell carcinoma, collecting duct carcinoma, and urothelial carcinoma (transitional cell carcinoma) of the kidney. Metastatic renal cell carcinoma to the bladder, liver, and lung subsequently developed. Deceptive inflammatory presentations can occur in aggressive synchronous renal malignancies. Recognition of this rare disease entity could prevent delays in diagnosis and treatment.