Alkaline-encrusted cystitis, a severe chronic infection of the bladder, was first described at the beginning of the century [1]. More recently, alkaline-encrusted pyelitis has been reported particularly in renal transplants [2] and also in native kidneys [3]. These two locations of the same infection are caused by urea-splitting microorganisms and are characterized by stone encrustation of the wall of the urinary tract. Although numerous bacteria have urease activity, Cornebacterium urealyticum is frequently the origin of the disease [2, 3].
This entity is a nosocomial infection and occurs in immunocompromised or debilitated patients after urological procedures. Because of an increasing number of renal transplants and other complex urologic procedures in an older or debilitated patient population, the risk of this nosocomial infection is likely to increase.
Our aim is to illustrate the radiologic characteristics of encrusted cystitis and pyelitis. Imaging is a major part of the diagnosis. When the infection is clinically and bacteriologically suspected, direct visualization on imaging of encrusted plaques should confirm the diagnosis. Moreover, when the infection is not suspected and is revealed by a nonspecific complication such as urinary tract obstruction, macroscopic hematuria, or renal failure, the radiologic visualization of encrusted plaques is strongly indicative of this entity.