A new cause of curvilinear renal calcification: calcified hydrocalycosis.

Although many causes of curvilinear renal calcifications have been described, calcified hydrocalycosis mimicking hydatid cyst has not previously been reported. We report a case of hydrocalycosis which was appeared as a curvilinear calcified cystic lesion resulted from staghorn calculus associated with xanthogranolomatous pyelonephritis (XGPN) on intravenous pyelography (IVU) and computed tomography (CT).