Renal abscess ,Xanthogranulomatous pyelonephtitis and Renal TuberculosisAUA Update series 2014 ,Volume 33 ,Lesson 36Pais ,sharmma ,Pattison et al

Anas Hindawi PGY3 Urology ResidentMakassed General HospitalBeirut Arab University

IntrodutionRetroperitoneal abscesses may arise from pathology originating sources most commonly the kidney

Kidney infections itself span a wide spectrum like acute uncomplicated acute pyelonephritis

Pyonephrosis ,Emphysematous Pyelonephritis pose true urologic emergencies

In this update we focus on Dx and Mgt. of 3 challenging manifestations of renal infection

Renal abscess ,Xanthogranulomatous pyelonephtitis and Renal Tuberculosis

Symptoms ,laboratory studies and imaging findings are non specific

Diagnostic and therapeutic arsenals reduce the associated significant morbidity and mortality

we will discuss pathophysiology ,diagnostic capabilities and treatment options applicable to those patients

Renal and Perinephric abscesses Renal abscesses are collections of pus within renal parenchyma ,further categorized by anatomical location

Perinephric abscess extend beyond capsule but contained by Gerota fascia ,commonly caused by rupture of renal abscess thru. Renal capsule , seeding of Perinephric Haematoma or Urinoma

An abscess extending through Gerota classified as Paranephric abscesses that may result from GI infectious process

Renal and Perinephric abscesses are reviewed together under the designation of renal abscess

Paranephric abscesses are beyond preview in this update

EpidemiologyRelatively uncommon (0.01% hosp. admissions)

Most often unilateral

No gender predilection

Prevalence increases with age

Etiologies include infected renal or ureteral stones ,non calculus renal obstruction (*) ,pyelonephritis ,UTI ,previous urological surgeries ,PCKD

Predisposing factors include : DM , steroids ,HIV ,IV drug abuse ,prior uncomplicated UTI ,liver disease ,pregnancy

15 % of abscesses occurred in patients without known predisposing factors

DM represents an important factor acc. To a population based study in which hazard ratio of hospitalization of 3.81 in DM patients was seen

DM was associated with lengthened hospitalization with no increase in mortality

PathogenesisThe advent use of antibiotics had led to earlier control and reduced hameatogenous spread of pyogenic G+ve infections shifting isolates to G-ve rods

Mot common organisms cultured are : E.coli ,Klebsiella ,Proteus ,Pseudomonas and staph. Aureus

It is suspected that Uropathogenic G-ve renal abscesses arise from ascending infection

Rarely renal abscesses reported to arise from ascending infection tracking up fascial planes from prostate abscess or s/p biopsy

PresentationClassic presentation of fever and unilateral flank pain in 23%

Common symptoms : Flank or abdominal pain ,palpable flank mass and voiding dysfunction

Insidious onset of chills ,N/V and weakness of less than one week duration

Laboratory findings of leulocytosis 90% ,pyuria 70%

Diagnosis Historically high degree of morbidity and mortality was referred to difficult diagnosis and delayed targeted treatment

Recently CT replaced x-ray and execratory urogram ,it provides anatomical and adequate assessment of infectionNon contrast CT findings of fluid filled lesion (0-40 HU) with or without gas ,Contrast enhanced films showed peripheral thickening and enhancement

Perirenal fluid and inflammatory stranding with thickened Gerota might present

CT is diagnostic in 90%

Ultrasound is particularly useful in :children ,pregnant ,patient preference ,following known abscess

Nonetheless Ultrasound sensitivity is much lower than CT in initial evaluation

Ultrasound findings are variable :hypoechoic ,hyperechoic , complex cystic or post. Acoustic enhancement

Doppler distinguish abscess from neoplastic lesion

Acute pyelonephritis is among the most common admission misdiagnoses

Typically diagnosis is made clinically and treated non surgically

Renal abscess distinguished from acute pyelonephritis by 2 features : 1) symptomatic > 5 days 2) fever > 5 days

Not all acute pyelonephritis pts. Needs imaging ,unless high suspicion of obstruction or dowentrending of fever curve does not follow conservative and IV antibiotics management

TreatmentEmpiric ABx therapy should cover the most common uropathogen /E-coli ,klebsiella ,proteus and less commonly haematogenous spread staph-aureus/

Culture data of abscess ,urine and blood has to be interpreted and considered

Concordance of abscess and urine cultures may be observed in 49%

Additional isolates might be seen in abscess but not vice-versa in urine

Small renal abscesses treated by IV ABx has to be observed for clinical improvement and changing of the course based on culture data

Selection of initial treatment modality depends on : size ,location of abscess ,overall clinical status

Efficacy of ABx therapy has been observed in smaller abscesses in immunocompetent patients

Reports/siegel et al ,dall palma et al ,comploj et al / of abscesses resolution smaller than 5 cm , solitary or multiple using broad spectrum ABx over 6 weeks in some of the reports

Patients with no clinical improvement should be offered a drainage procedure

ABx without drainage is not recommended in gravely ill immunocompromised pts

Abscesses > 3cm in immunocompromised pts regardless the size not responding to ABx alone require drainage in combination with culture directed ABx

Ultrasound and CT guided drainage allow excellent targeting and confirmation of appropriate drain placement

Yen et al reported 76% resolution rate of intrarenal/perinephric abscesses treated by percutaneous drainage with no description of the size

Siegel et al reported 92% resolution rate for 3-5 cm intrarenal/perinephric abscesses with percutaneous drainage

This approach proved to be useful even in >10 cm abscesses

Meng et al reported successful approach in 7/11 abscesses with average size 11 cm ,all >5 cm

Patients had longer hospitalization ,multiple drain manipulations ,prolonged catheter placement

Siegel et al reports a high failure rate of larger abscesses

Loculations do not appear to be a contraindication

Open surgical approach may be considered in suspected GI involvement ,large complex or multiloculated collections ,non functioning kidney

Nephrostomy tube or uretral stent should be performed in the setting of obstruction and infection

Follow upProgress should be monitored to confirm clinical improvement

Imagings /CT ,ultrasound/ are recommended to confirm resolution of abscesses

There are no evidence based protocols to direct a course of follow up imaging

Xanthogranulomatous pyelonephritisXGP is a chronic inflammatory condition of the kidney distinguised by replacement of the renal parenchyma with granulomatous collections of lipid laden histocytes

XGP is associated with chronic infection and obstruction leading to enlarged poorly or non functioning kidney

Might mimic any other urological condition

CT & MRI might show neoplastic process changes

Epidemiology XGP is identified in 8.2-19% of biopsies or nephrectomies performed for chronic pyelonephritis

Annual incidence not sufficiently reported 1.4/100.000

5th to 6th decades age average ,3/1 female to male

Predisposition factors : UTI ,nephrolithiasis

Diabetes as frequent co morbidity

PathophysiologyXGP most commonly encountered with chronic renal infection ,nephrolithiasis and obstruction

Definitive correlation is poor for renal ischaemia ,lymphatic and venous obstruction ,impaired immune response and altered lipid metabolism a causative factor

Concomitant infection with obstruction reported in significant numbers

Nephrolithiasis is present in 82%

Urine cultures reveal G-ve uropathogens ,indicating ascending infection

Proteus and E-coli are the most common offending agents

Pseudomonas ,staphylococcus ,klebsiella , candida and anaerobs are reported

In light of frequently associated upper tract obstruction ,urine cultures can be negative in up to 40% and when positive discordant

Presentation Several months symptoms are common

Constitutional symptoms of weight loss ,malaise ,fever

Examination may reveal tender palpable mass ,unilateral CVA tenderness 72%

Findings indicating fistulization or local spread such as a draining flank sinus or empyema

Leukocytosis ,elev. ESR and anemia ,liver dysfunction might present and reolve by Tx

DiagnosisClinically ,radiologically and histologically non specific features confused with renal cell carcinoma ,malacoplakia ,renal TB ,renal infarction ,pyonephrosis and wilms tumor Radiographic findings of classic non functioning enlarged kidney ,nephrolithiasis in up to 80%CT is the optimal modality for imaging and diagnosing XGP CT findings suggests presence of diffuse XGP are : poorly defined renal pelvis ,diminished renal pelvis fat ,hypoechoic non enhancing spherical nodules ,rim like enhancement around the mass ,air in urinary tract 9.8% with no typical emphysematous pyelitis/pyelonephritis

US may reveal hydronephrosis , stone ,pyenephrosis evidenced by internal ehoes from pus or debris in renal pelvisFocal form most commonly confused with tumors and abscesses ,with no reliable findings to differentiateMRI offers no data above CT ,not routinely performedThe gold standard of XGP diagnosis is still pathological examination s/p nephrectomyGross examination reveal indurated adherent perinephric fat ,parenchymal and peripelvic fibrosis ,pus filled calyces or renal pelvisMicroscopic evaluation shows replacement of normal renal parenchyma by sheets of lipid laden macrophages /xanthoma cells/

TreatmentSurgical excision remains the treatment of choice Appropriate timed surgical excision avoid extrarenal spread and potential of more complicated and morbid procedures

In diffuse XGP ,there is no functional parenchyma radical nephrectomy is the preferred treatment /open nehrectomy/

The benefits of laparoscopy do not extend to XGP

Partial nephrectomy of focal XGP is considered

Nephron sparing approach is feasible with no recurrence rate even in bilateral focal XGP

Non operative management may be an appropriate consideration for children

Renal tuberculosis

Caused by haematogenous seeding of mycobacterium TB from pulmonary focus

Seeding occurs at the level of glomerular capillaries ,grow insidiously years after initial infection

Caseating granulomas occur within kidneys and spread distally through the urinary system

EpidemiologyIncidence in U.S of 3.2/100,000 ,decline in last 20 ysRenal TB decline in association with pulmonary TB declineGenitournary TB represents 6.5% of extrapulmonary TB Higher infection and high reactivation populations are at risk of renal TBHigher infection in : foreign born ,homelss ,resident and workers at health care facilitiesHigher reactivation in : HIV ,drug abusers ,DM ,low body weight ,immunocompromised ,chronic inflammatory dis.and transplants

Presentation Non specific intermittent chronic urinary symptoms and some asymptomatic

Most common symp. Of renal TB is : frequency then dysuria and flank pain

Often have chronic sterile pyuria with/out microscopic haematuria

Typical symptoms of TB are rare

Renal TB often presents with late stage complications such as hydronephrosis/pyonephrosis or obstructive uropathy

Renal function rarely affected even in advanced stages

Late stage complications include formation of a sinus tract ,complicated renal cysts ,thight abscesses ,perirenal haemorrhage and auto-nephrectomy

Diagnosis No testing method has adequate sensitivity/specificity to diagnose renal TBShould be suspected with persistent sterile pyuria despite standard TxCombination of microscopic haematuria and sterile pyuria can be suggestive of renal TB with other reisk factors or +ve tuberculin testSerial cultures yield variable sensitivity /80%/ after 6 weeks growthHigh cost culture techniques emerged with limited data

Single step PCR provides rapid method of detection with higher specificity 95-100% , sensitivity 25-95%

Clinical usefulness is limited by commercial availability of detection kits

Imaging is faster method than culture ,more available than PCR

1/3 of renal TB have a +ve chest x-ray findings

Execratory urography when CT unavailable or radiation exposure is a concern

Early changes of blunting or minor calyces ,late changes are calcifications and lost calyx due to infundibular stenosis

Common findings include hydrocalycosis ,hydronephrosis and hydroureter due to uretral strictures

Retrograde pyelogram can delineate pelvicalyceal abnormalities that can be seen either unilateral or bilateral

CT provides information abt pulmonary and extra-pulmonary involvement

Better than plain films in detecting renal parenchyma masses , scarring ,thick urinary tract wall ,non uniform calicectasis and dense calcifications

MRI is a good option in renal insufficiency ,contrast allergy and radiation concerns

Medical treatmentRandomized control trials are performed on the medical management of genitourinary TB ,consensus exist on the efficacy of 6 months antituberculosis chemotherapy

Goals of Tx are cure , spreading control and prevent further drug resistant

Standard six months chemotherapy with multi drugs /isoniazid ,rifampin ,pyrizinamide and ethambutol/

1st two months with all 4 drugs ,last four months with 2 drugs

Surgical treatmentMedical treatment is adequate in uncomplicated renal TB

Surgical management is indicated for : hydronephrosis ,abscess drainage ,infected non functioning kidney removal ,urinary tract reconstruction for strictures

Stenting success rate 40-60%

Partial nephrectomy indicated in calcified lesions non responding to chemotherapy or growing in sizetotal nephrectomy is indicated in :non functioning kidney ,diffuse pattern ,UPJ obstruction and HTN and coexisting RCC

Reconstruction is indicated for complex stricture like long segments ,extensive bilateral involvement and impassable strictures

Simple strictures ,short segments that are passable in setting of salvageable renal function can be managed endoscopically

Controversies There is debate among researchers abt. :

Use of corticosteroids in distal ureteral strictures management Antituberculosis chemotherapy duration /4 vs 6 mths./Need for safe sex practice Timeline for invasive procedures in relation to chemotherapy Usefulness of total nephrectomy for asymptomatic tuberculous kidney

Follow upThe AUA recommends follow up schedule at 3 ,6 and 12 months , some suggest longer follow up surveillance

The EAU advocates weekly IV pyelogram to monitor for distal uretral obstruction while on chemmotherapy /due to oedema/

Recent german review suggests follow up of 5 ys after antituberculosis Tx

Corticosetroids can be used f no improvement after 3 weeks

Fibrosis can occur after completion of therapy