Unilateral Medullary Sponge Kidney

A 40-year-old female with an allergy to medium contrast, presented with bilateral loin pain and renal colic type radiation. Image study with non-contrast computerized tomography and magnetic resonance imaging revealed multiple nephrolithiasis and a complex cyst at lower pole of the right kidney and no findings in the left one. The patient was treated with laser lithotripsy by flexible ureterorenoscopy revealing multiple lithiasis within cystic dilatations of the urothelium. The complex cyst was submitted to partial nephrectomy. Finally, biopsy demonstrated that it was renal parenchyma with polycystic changes in the external corticomedullary area. All findings were compatible with unilateral medullary sponge kidney diagnosis.