Gas containing renal stone - case report.

Gas-containing stones are extremely rare. The formation of renal stones, including the presence of free gas within the stone, is overall poorly understood. The presence of free gas in the collecting system of the urinary tract indicates emphysematous pyelonephritis, in the absence of prior surgical intervention, gastrointestinal fistula, or urinary bladder catheterization. Here, we present the tenth case of gas-containing renal stones, as detected by computed tomography, and discuss the main diagnostic features to differentiate gas-containing stones from emphysematous pyelonephritis.