Teaching Case

The patient was admitted for thigh mass study. Previously, he had bladder cancer treated by transurethral resection, without having undergone any other urologic procedures. Mass biopsy result was a high grade pleomorphic sarcoma. Neither fever nor abdominal pain were present. Normal urinary output. Creatinine level showed slight fluctuations. Routine urine culture was sterile.

Abdominal X-ray film showed no calcification. Ultrasound of the kidney detected mild right hydronephrosis and hyperechogenic material in the pelvicalyceal cavities. Staghorn calculus was observed in low calyceal cavities, and intravesical. A new CT examination revealed multiple lung nodules suggestive of metastasis. CT of the abdomen confirmed the ultrasound findings.

Alkaline-encrusted pyelitis is a rare chronic infectious and inflammatory condition of the renal pelvis characterised by calcific deposits on the urothelium. This process may involve the urinary bladder (alkaline-encrusted cystitis). Although the numerous bacteria display urease activity, Corynebacterium group D2 (C. Urealyticum) is frequently the origin of this disease [1-3]. It has been typically described in immunocompromised or debilitated patients who have undergone urologic procedures. Usually a commensal organism of the skin, Corynebacterium group D2 may become pathogenic and infect the urinary tract in these patients. This may also occur in patients receiving prolonged antibiotic therapy [1].
Patients usually present macroscopic haematuria and deteriorating renal function [1, 4, 5]. Other features that have been reported are fluid overload [1], pyuria [1], suprapubic pain [2, 4], and passage of calcified and noncalcified mucopurulent debris [3] and stones [4], which can be responsible for acute obstructive uropathy [2]. Fever is inconstant [2].
Encrusted pyelitis can be minimally symptomatic for a long period of time [3]. A timely diagnosis of this condition will prevent an end-stage renal failure obviating the need for permanent dialysis [1].
The cornerstone of imaging diagnosis is the detection of urothelial calcifications by means of unenhanced CT. The calcifications can either be thin and regular or thick and irregular [4]. Additional CT examinations may detect renal pelvic wall thickening and oedema, as well as perinephric and periureteral inflammatory stranding [4]. Involvement can be uni- or bilateral [5]. Urothelial calcifications may or may not be evident on radiographs [4]. Ultrasonography may depict the urothelial calcifications as hyperechoic foci with or without acoustic shadowing, or it may yield normal findings [5].
CT findings in the appropriate clinical environment are suggestive of alkaline-encrusted pyelitis or cystitis. The diagnosis is usually confirmed microbiologically by isolating Corynebacterium group D2 bacteria from urine or nephrostomy aspirate. Successful culture of the bacteria requires prolonged incubation times of over 48 hr on special culture media [2]. Therefore, laboratory orders should be specifically requested to include an isolation of this bacterium to avoid both false-negative cultures and diagnosis delays.
Treatment consists of specific antibiotic therapy and dissolution of encrusted plaques containing the bacteria not affected by antibiotics (urine acidification with oral urease inhibitors or direct urine acidification with irrigation via nephrostomy catheters). In the bladder, endoscopic resection of encrustations can be performed, but in the upper urinary tract, resection is difficult [2] and may be dangerous [5].