AJR 2002; 178:389-392
© American Roentgen Ray Society
Imaging Characteristics of Alkaline-Encrusted Cystitis and Pyelitis
Denis Thoumas1,
Caroline Darmallaicq2,
Christian Pfister3,
Céline Savoye-Collet1,
Louis Sibert3,
P. Grise3,
Laurent Lemaitre2 and
Michel Benozio1
1
Department of Radiology, Rouen University Hospital-Charles Nicolle, 1 Rue de
Germont, 76031 Rouen Cedex, France.
2
Department of Radiology, Lille University Hospital-Claude Huriez, Rue
Polonovski, 59037 Lille Cedex, France.
3
Department of Urology, Rouen University Hospital-Charles Nicolle, 76031 Rouen
Cedex, France.
Received December 18, 2000;
accepted after revision August 28, 2001.
Address correspondence to D. Thoumas.
Introduction
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 in the wall of the urinary tract.
Although numerous bacteria have urease activity, Corynebacterium
urealyticum is frequently the origin of this disease
[2,
3].
This entity is a nosocomial infection and occurs in immunocompromised or
debilitated patients after urologic 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.
Physiopathology
C. urealyticum is a gram-positive commensal microorganism of the
skin [4]. Urinary infections
due to this bacterium are nosocomial
[3,
4] and require three conditions
to cause alkaline-encrusted cystitis or pyelitis: a clinical context with
immunosuppression or prolonged antibiotic therapy; a urologic procedure either
surgical or endoscopic, responsible for contamination of the urinary tract;
and an inflammatory or neoplastic preexisting lesion of the urothelium
providing a favorable environment for stone encrustation
[3,
4].
This bacterium is a urease-producing microorganism transforming urea into
ammonia. This urease activity explains the modification of pH in urine, which
becomes alkaline, leading to formation of struvite and calcium phosphate.
These substances are responsible for wall encrustation on pathologic mucosa or
stone formation.
The specific diagnosis of C. urealyticum infection may be missed
by a standard urine culture and requires a prolonged incubation for more than
48 hr on special media [3]. In
some reported cases, this bacterium was not found because it was not
specifically sought [2,
5].
Clinical and Biologic Data
Encrusted cystitis usually presents with dysuria and suprapubic pain.
Encrusted pyelitis can be minimally symptomatic for a long period. Fever is
inconstant [3]. Macroscopic
hematuria with elimination of stones and an ammonia odor of the urine are
strongly indicative of this infection. It may be also revealed by a clinical
consequence such as acute obstruction or loss of renal function in patients
with transplants.
The major characteristic of this infection is its clinical context. Most
patients have a previous history of urologic disease and have undergone
urologic procedures. The delay between the urologic procedure and the
diagnosis can vary up to several years
[3]. Immunosuppression or
prolonged antibiotic use have been found in most cases
[3].
Urine analysis is also characterized by alkaline pH, pyuria, hematuria, and
struvite crystals.
Endoscopic and Histologic Data
On cystoscopy, encrusted cystitis is characterized by an inflammatory
mucosa with ulcerations and superficial whitish plaques corresponding to
encrusted calcifications.
A reported macroscopic image of a kidney transplant removal for encrusted
pyelitis revealed marked thickening of urothelial walls with superficial
calcifications [6]. At
histologic examination of the collecting system, three layers could be
differentiated: a superficial layer with necrosis and microcalcifications; an
intermediate layer with inflammatory changes; and a third layer corresponding
to bladder muscularis in encrusted cystitis and to normal renal parenchyma in
encrusted pyelitis.
Radiologic Data
Alkaline-encrusted cystitis or pyelitis is defined by stone encrustation of
the urinary tract wall, which can be depicted on an abdominal radiograph. In
the bladder, when calcification outlines the bladder wall, the diagnosis is
simple [7]. In the upper
urinary tract, when calcification is bulky or associated with free stones and
could be mistaken for a staghorn calculus, the diagnosis can be more difficult
[5]. Moreover, calcification of
encrusted pyelitis may be radiolucent (Figs.
1A,1B,1C
and
2A,2B,2C).
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Fig. 1A. —52-year-old mentally ill institutionalized man with
neurogenic bladder who was hospitalized for fracture of right femoral neck 1
month before imaging. Bladder catheter was placed during postoperative period.
Patient presented with acute bladder obstruction after period of dysuria and
macroscopic hematuria. Unenhanced radiograph of pelvis fails to show bladder
calcification.
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Fig. 1B. —52-year-old mentally ill institutionalized man with
neurogenic bladder who was hospitalized for fracture of right femoral neck 1
month before imaging. Bladder catheter was placed during postoperative period.
Patient presented with acute bladder obstruction after period of dysuria and
macroscopic hematuria. Sonogram of bladder reveals thickening of bladder wall
with two distinct layers. Superficial layer (white arrow) is
echogenic, corresponding to encrustation of urothelium. Underlining layer
(black arrow) is hypoechogenic, corresponding to detrusor.
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Fig. 1C. —52-year-old mentally ill institutionalized man with
neurogenic bladder who was hospitalized for fracture of right femoral neck 1
month before imaging. Bladder catheter was placed during postoperative period.
Patient presented with acute bladder obstruction after period of dysuria and
macroscopic hematuria. Unenhanced CT scan shows tiny calcifications in
urothelium. Encrustation is thin, regular, and superficial. Findings of
specific search were positive for Corynebacterium urealyticum, and
patient was successfully treated by local acidification, transurethral
resection of plaques, and antibiotic therapy.
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Fig. 2A. —34-year-old woman hospitalized for asthenia, worsening of
chronic renal insufficiency, and hematuria. Patient was treated during infancy
for congenital uropathy and had single left kidney with sigmoid loop
diversion. She underwent surgery 6 months before admission for ureteropelvic
junction obstruction. Unenhanced CT scan with patient in prone position shows
thick calcification of urothelial wall, not mobile in prone position.
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Fig. 2B. —34-year-old woman hospitalized for asthenia, worsening of
chronic renal insufficiency, and hematuria. Patient was treated during infancy
for congenital uropathy and had single left kidney with sigmoid loop
diversion. She underwent surgery 6 months before admission for ureteropelvic
junction obstruction. Abdominal radiograph, obtained day after placement of
nephrostomy tube, shows that this encrustation, obvious on CT scan (A),
is not visible.
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Fig. 2C. —34-year-old woman hospitalized for asthenia, worsening of
chronic renal insufficiency, and hematuria. Patient was treated during infancy
for congenital uropathy and had single left kidney with sigmoid loop
diversion. She underwent surgery 6 months before admission for ureteropelvic
junction obstruction. Unenhanced CT scan after antibiotic therapy and local
acidification through nephrostomy tube reveals some residual calcification,
but patient was asymptomatic, with urine cultures negative for
Corynebacterium urealyticum.
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Sonography is also a useful diagnostic tool when calcification can be
visualized in the urothelium and not in the lumen of the urinary tract. This
situation occurs when calcification lies in the wall of a dilated pelvis or in
a full bladder (Figs.
1A,1B,1C,
3A,3B,3C,
and
4A,4B,4C,4D).
In the caliceal system, this encrustation is difficult to differentiate from
staghorn calculus (Fig.
4A,4B,4C,4D).
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Fig. 3A. —24-year-old woman with gradually increasing serum creatinine
level 5 months after renal transplantation. Endovaginal sonogram (A)
and unenhanced CT scan (B) show thickening of bladder wall with
encrusted calcification.
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Fig. 3B. —24-year-old woman with gradually increasing serum creatinine
level 5 months after renal transplantation. Endovaginal sonogram (A)
and unenhanced CT scan (B) show thickening of bladder wall with
encrusted calcification.
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Fig. 3C. —24-year-old woman with gradually increasing serum creatinine
level 5 months after renal transplantation. Multiplanar reconstruction of CT
performed after opacification of collecting system by nephrostomy tube
injection shows bladder calcification (arrow) at ureterovesical
junction. Bladder-shape deformity is due to curve reconstruction.
Corynebacterium urealyticum was found in urine culture, and patient
was treated with specific antibiotic therapy and transurethral resection of
calcified plaques.
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Fig. 4A. —74-year-old man admitted in emergency department for
hematuria, pyuria, left-sided back pain, asthenia, and fever. Before
admission, patient had a long medical history of urologic diseases, radical
prostatectomy (15 years earlier), right ureteronephectomy (11 years earlier),
cystectomy, and left ureterostomy (9 years earlier) for urothelial
transitional cell carcinoma. Subsequently, he presented with numerous
infections and stones in remaining kidney. Sonography and CT performed in
emergency department suggested diagnosis of encrusted pyelitis, which was
confirmed by specific urine culture. Local acidification through nephrostomy
tube was performed, but patient died a few days later from cardiac failure.
Longitudinal sonogram of left kidney shows hyperechogenic structures
(arrows) in calices with acoustic shadowing that could correspond to
encrustation or free stones.
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Fig. 4B. —74-year-old man admitted in emergency department for
hematuria, pyuria, left-sided back pain, asthenia, and fever. Before
admission, patient had a long medical history of urologic diseases, radical
prostatectomy (15 years earlier), right ureteronephectomy (11 years earlier),
cystectomy, and left ureterostomy (9 years earlier) for urothelial
transitional cell carcinoma. Subsequently, he presented with numerous
infections and stones in remaining kidney. Sonography and CT performed in
emergency department suggested diagnosis of encrusted pyelitis, which was
confirmed by specific urine culture. Local acidification through nephrostomy
tube was performed, but patient died a few days later from cardiac failure.
Axial sonogram of left kidney shows dilated renal pelvis with superficial
calcification in pelvis wall (arrow).
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Fig. 4C. —74-year-old man admitted in emergency department for
hematuria, pyuria, left-sided back pain, asthenia, and fever. Before
admission, patient had a long medical history of urologic diseases, radical
prostatectomy (15 years earlier), right ureteronephectomy (11 years earlier),
cystectomy, and left ureterostomy (9 years earlier) for urothelial
transitional cell carcinoma. Subsequently, he presented with numerous
infections and stones in remaining kidney. Sonography and CT performed in
emergency department suggested diagnosis of encrusted pyelitis, which was
confirmed by specific urine culture. Local acidification through nephrostomy
tube was performed, but patient died a few days later from cardiac failure.
Unenhanced CT scan shows thickening of urothelial wall with superficial
encrustation and stranding in surrounding soft tissue.
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Fig. 4D. —74-year-old man admitted in emergency department for
hematuria, pyuria, left-sided back pain, asthenia, and fever. Before
admission, patient had a long medical history of urologic diseases, radical
prostatectomy (15 years earlier), right ureteronephectomy (11 years earlier),
cystectomy, and left ureterostomy (9 years earlier) for urothelial
transitional cell carcinoma. Subsequently, he presented with numerous
infections and stones in remaining kidney. Sonography and CT performed in
emergency department suggested diagnosis of encrusted pyelitis, which was
confirmed by specific urine culture. Local acidification through nephrostomy
tube was performed, but patient died a few days later from cardiac failure.
Unenhanced CT scan at lower pole of left kidney shows encrustation in
ureter.
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CT appears to be the optimal technique to diagnose encrustation,
particularly in the upper urinary tract. CT is a more sensitive technique to
detect calcification even if it is thin or radiolucent on radiographs (Figs.
1A,1B,1C,
2A,2B,2C,
and
5A,5B).
CT permits excellent visualization of the urothelial wall and of calcification
(Fig.
4A,4B,4C,4D).
This calcification superficially covers the urothelium; it can be thin and
regular (Fig. 6) or thick and
irregular (Fig.
2A,2B,2C).
Moreover, CT shows urothelial wall thickening and, in severe infections,
perinephric and periureteral changes with soft-tissue stranding (Fig.
4A,4B,4C,4D).
Contrast media injection is not necessary for the diagnosis.
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Fig. 5A. —55-year-old woman hospitalized for macroscopic hematuria,
back pain, and fever 2 years after ileal loop diversion. Routine urine culture
was negative for Corynebacterium urealyticum. Findings of unenhanced
radiograph of abdomen (not shown) and sonogram of kidneys (not shown) were
normal. Unenhanced CT scans show slight calcification (white arrows)
of both renal pelves. Calcification in left renal pelvis underlines thickening
of pelvis wall (black arrow). Image is more suggestive of
encrustation than of staghorn calculi, and encrusted pyelitis was confirmed by
findings of Corynebacterium urealyticum on specific urine culture.
Patient was successfully treated with oral acidification of urine and specific
antibiotic therapy.
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Fig. 5B. —55-year-old woman hospitalized for macroscopic hematuria,
back pain, and fever 2 years after ileal loop diversion. Routine urine culture
was negative for Corynebacterium urealyticum. Findings of unenhanced
radiograph of abdomen (not shown) and sonogram of kidneys (not shown) were
normal. Unenhanced CT scans show slight calcification (white arrows)
of both renal pelves. Calcification in left renal pelvis underlines thickening
of pelvis wall (black arrow). Image is more suggestive of
encrustation than of staghorn calculi, and encrusted pyelitis was confirmed by
findings of Corynebacterium urealyticum on specific urine culture.
Patient was successfully treated with oral acidification of urine and specific
antibiotic therapy.
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Fig. 6. —75-year-old woman with acute renal obstruction of right
solitary kidney. Patient had history of bladder urothelial transitional cell
carcinoma treated by resection and radiotherapy several months before
admission. Unenhanced CT scan shows thickening of urothelial wall with
superficial, regular, and thin encrustation underlining renal pelvis,
infundibula, and calyces. Note ureteral stent (arrow) placed because
of stone migration from calcified plaques. Specific search was positive for
Corynebacterium urealyticum.
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The effective accuracy of each technique to detect encrusted plaques is
difficult to assess because of the rarity of this disease. Nevertheless, most
authors emphasized the critical role of CT with native kidneys
[5] or renal transplants
[8].
Diagnosis
Medical history, clinical context, and urine analysis associated with
radiologic findings are basic elements used in the diagnosis of encrusted
cystitis or pyelitis. The diagnosis is confirmed by showing a urea-splitting
micro-organism on urine culture. However, urothelial wall encrustation,
particularly in the bladder, can also be observed in schistosomiasis,
tuberculosis, necrotic urothelial carcinoma, leucoplakia, or after
intravesical instillations of cyclophosphamide or mitomycin
[7].
Treatment
The treatment of encrusted cystitis or pyelitis must achieve two goals:
bacterium eradication with a specific antibiotic therapy and a dissolution of
encrusted plaques that contain the bacteria not affected by antibiotics. In
the bladder, endoscopic resection of encrustations can be performed, but in
encrusted pyelitis, resection is difficult
[3] and may be dangerous
[5]. In cases of encrusted
pyelitis, if encrustation is thin and not too extensive, oral acidification of
the urine may be sufficient to ensure plaque dissolution. When encrustation is
thick and extensive, a local acidification should be performed; thick and
extensive encrustation requires the placement of a percutaneous nephrostomy to
permit local irrigation with acid solution and a ureteric stent to ensure
outflow [3]. Again, CT should
be considered in deciding optimal treatment and in monitoring the regression
of calcified plaques.
Summary
Alkaline-encrusted cystitis or pyelitis is a chronic severe urinary tract
infection. Urothelium stone encrustation is the main characteristic of this
infection and can be seen radiographically particularly on unenhanced CT.
Imaging is useful for diagnosis and to determine and monitor effective
treatment.
Acknowledgments
We thank Richard Medeiros for his editorial assistance.
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Introduction
Physiopathology
