Alkaline-Encrusted Cystitis and Pyelitis

Alkaline-encrusted cystitis and pyelitis refer to stone encrustation in the wall of the urinary tract caused by urea-splitting microorganisms. This is a nosocomial infection that typically occurs in immunocompromised or debilitated patients after urologic procedures.

CT is the imaging modality of choice for demonstrating encrustation, particularly in the upper urinary tract. CT shows calcifications superficially covering a thickened urothelium. The calcifications can be thin and regular or thick and irregular. Perinephric and periureteral stranding may be seen with severe infection.

Ultrasound may show urothelial calcifications in a dilated renal pelvis or a full bladder. Calyceal calcifications, on the other hand, cannot be reliably differentiated from stag-horn calculi by ultrasound.

Planar radiography may show the calcifications, but is obviously not very sensitive.

Differential considerations include other causes of urothelial wall encrustation:

• Schistosomiasis
• Tuberculosis
• Necrotic urothelial carcinoma
• Leucoplakia
• Intravesical instillation of cyclophosphamide or mitomycin.

References

Thoumas D, Darmallaicq C, Pfister C, Savoye-Collet C, Sibert L, Grise P, Lemaitre L, Benozio M. Imaging characteristics of alkaline-encrusted cystitis and pyelitis. AJR Am J Roentgenol. 2002 Feb;178(2):389-92.