This document provides an overview of various renal infectious and inflammatory diseases. It begins by outlining pyelonephritis, including predisposing factors, clinical presentation, imaging findings on ultrasound, CT, and pathology. Complications of pyelonephritis such as abscesses, emphysematous pyelonephritis, and pyonephrosis are then reviewed. The document concludes by discussing other infectious conditions including tuberculosis, xanthogranulomatous pyelonephritis, renal malakoplakia, and fungal disease. Imaging findings and characteristics of each condition are emphasized.

1. Renal
Infectious/Inflammato
ry Disease
Jud Gash, MD

2. Outline
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Pyelonephritis
Renal Abscess
Emphasematous Pyelonephritis
Pyonephrosis
Xanthogranulomatous Pyelonephritis
TB
Renal Malakoplakia
Other Infection

3. Pyelonephritis

Predisposition

Most cases similar to lower UTI causes (esp intercourse)



About 20-30:1 cystitis to PN
Female, reflux, obstruction, stones, diabetes, stasis
(congenital anomalies, diverticula), pregnancy
Clinical


Gram negatives (E coli, Proteus, Pseudomonas, etc.)
Flank pain and tenderness, fever, N/V, signs of cystitis

4. Pyelonephritis

Imaging


Usually not necessary (uncomplicated PN)
Reasons to image
Uncertain diagnosis
 Severe symptoms
 Atypical clinical situation


men, unresolving, children, diabetics
Role out obstruction
 Evaluate source in recurrent pyelonephritis



May see incidentally
Note: imaging of PN/UTI in children whole separate
topic

5. Pyelonephritis

Pathophysiology

Ascending Infection


Adhesions and
Endotoxins
Ureteropyelitis



Pyelonephritis



Thickened, enhancing
Urothelium
Ureteral “ileus”
Access/spread via
papilla
Wedge shaped and
patchy
Rarely hematogeneous


Staph
Bilateral

6. Ultrasound

Role
Detect Complications



Pyonephrosis; abscess
Predisposing factors
Scarring
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

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Imaging
Normal (75%?)
Enlargement
Loss of corticomedullary
junction
Decreased Echogenecity


Hyperechoic (hemorrhage)


Focal or diffuse
Focal
Hypoechoic area on Power
Doppler

7. Severe unilateral acute bacterial pyelonephritis
Craig W D et al. Radiographics 2008;28:255-276

8. Craig W D et al. Radiographics 2008;28:255-276

9. Pyelonephritis
Radiographics. 2000;20:215-243
Craig W D et al. Radiographics 2008;28:255-276

10. Pyelonephritis

CT

Noncontrast

Normal
Nephromegaly
 Perinephric stranding
 Loss of hyperdense pyramids
 Hyperdensities (hemorrhage)
 Thickening of urothelium
 Mild ureteral dilation
Contrast
 Wedges of hypoattenuation (edema, obstruction, and vasospasm)
 Dense on delayed
 Striations (focal, diffuse)
May be abnormal for days or weeks
Role






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Diagnosis/alternative diagnosis
Acute complications
Underlying predispositions (CTU)

11. ED – flank pain (no stone seen)

12. Pyelonephritis

DDX





PN
Recent stone passage
Non-stone obstruction (clot,
fungus ball, iodinovir)
Acute vascular lesion (RA, RV
occlusion)
So, non-contrast findings
nonspecific.


Clinical exam/UA/hydro should
allow distinction
Consider contrast if unclear
RadioGraphics 2004;24:S11-S28

13. Craig W D et al. Radiographics 2008;28:255-276

14. Craig W D et al. Radiographics 2008;28:255-276

15. Pyelonephritis
RadioGraphics 2004;24:S11-S28

16. Pyelonephritis
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

17. Acute bacterial pyelonephritis caused by hematologic
seeding in a patient with Staphylococcus aureus
endocarditis
Craig W D et al. Radiographics 2008;28:255-276

18. Pyelonephritis – DDX (3 I’s)
Radiographics. 2000;20:215-243

19. Pyelonephritis

Focal Pyelonephritis
Replaces old terms (FLN,
ABN, etc.)
 May be pre-abscess state
 Now focal or diffuse
pyelonephritis
 Imaging


Focal mass-like lesion can
mimic tumor

20. Complications of Pyelonephritis

Acute

Abscess





Renal
Perinephric
Emphysematous PN
Pyonephrosis
Chronic



Scarring/Atrophy
XGP/malakoplakia
Papillary Necrosis

21. Abscess

Etiology
PN which proceeds to tissue necrosis and
liquefaction
 More likely with obstruction, diabetes (75% of all
abscesses), stone disease
 Normal kidneys or superinfect pre-existing lesions
(cysts, diverticula, RCC)
 Can spread to perinephric space


22. Abscess

Imaging

US
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CT
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Rounded, thick wall cystic
mass with debris
Rounded cystic lesion with
enhancing wall
Surrounding inflammatory
changes
Microabscesses

Small, often multiple areas
in the setting of PN
RadioGraphics 2004;24:S11-S28

23. Perinephric Abscess

Usually secondary
to pyonephrosis

Less commonly in
unobstructed PN
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

24. Emphysematous Pyelonephritis





Aggressive form of PN with necrosis, vascular
compromise and air production
Rare life threatening form urologic emergency
90% diabetics (poorly controlled)
Obstruction common (must exclude)
Adults


Rare, if ever, seen in pediatrics
Clinical presentation


Fever, flank pain, lethargy, renal failure, septic shock
Usually gram negatives, esp. E. Coli

25. Emphysematous Pyelonephritis

KUB



Gas collections
Renal Enlargement
Stones
Radiographics. 2002;22:543-561

26. Emphysematous Pyelonephritis

27. Emphysematous Pyelonephritis

28. Emphysematous Pyelonephritis

29. Emphysematous Pyelonephritis
Radiographics. 2002;22:543-561

30. Emphysematous Pyelonephritis

US
Hyperechoic dirty
shadowing
 DDX: nephrocalcinosis
and nephrolithiasis


31. Emphysematous Pyelonephritis
Radiographics. 2002;22:543-561

32. Emphysematous Pyelonephritis

CT
Parenchymal air – bubbles,
linear
 Severe inflammatory
changes
 Look for obstruction

Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

33. Emphysematous Pyelonephritis

Treatment
Nephrectomy –
traditional gold
standard
 If more limited,
milder form –
percutaneous
drainage/relief of
obstruction and
antibiotics

Radiographics. 2002;22:543-561

34. Emphysemtous pyelitis



Gas in collecting
system
Same epidemiology
as EPN
Better prognosis

Relief of
obstruction/ABX

35. Emphysemtous pyelitis
Air In Collecting System



Emphysematous Pyelitis
Fistula
Iatrogenic
Radiology. 2001;218:647-650

36. Pyonephrosis


Obstructed, infected kidney
Cause of obstruction


Stones (rarely other: Conj UPJ, tumor)
Emergency
Urosepsis
 Renal destruction
 XGP (chronic)


Treatment

Drainage (perc neph/stent and antibiotics)

37. Pyonephrosis

US

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Large, hypoechoic kidney
Hydronephrosis
Echogenic debris
Fluid – Fluid Level
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

38. Pyonephrosis – 4 cases

39. Pyonephrosis
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CT
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
Findings of infection
Findings of obstruction
Hypedense/debris in collecting
system


Thick pelvic pelvic wall (2-5mm)



>30 hu (Note: 50%<15hu)
75% (Note: 10% of uninfected
obstruction)
Emphysematous pyelitis in 10%
Aspirate Urine

40. Chronic Pyelonephritis


Controversial
Pathophysiology
Findings
Renal Scarring
 Calyceal Clubbing
 At Renal Poles


DDX

Renal infarcts

41. Xanthogranulomatous Pyelonephritis
(XGP)


Disorder immune response in
setting of chronic infection, often
with obstruction and stones (ie
pyonephrosis)
Pathophysiology




Stone leads to obstruction
Caliectasis (peripelvic fibrosis limits
pelviectasis).
Infection leads to parenchymal
destruction and replacement with
lipid laden macrophages
Treatment

nephrectomy
Radiographics. 2000;20:215-243

42. Xanthogranulomatous Pyelonephritis
(XGP)

Key points

Middle age women with longstanding
infection/stones


DM in only 10%
Triad
Nonfunction
 Renal enlargement



Caliectasis with less pelviectasis, parenchymal loss
Stones (90%)

Staghorn, exploded

43. Xanthogranulomatous Pyelonephritis
(XGP)

KUB


“exploded” staghorn
with large renal
shadow
US
Caliectasis (massive)
with debris
 Stones

Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

44. Xanthogranulomatous Pyelonephritis
(XGP)

CT


“Bear Claw”
Massive caliectasis (without
pelviectasis)



Not fluid though
Parenchyma enhances (not
function)
Stones
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

45. Xanthogranulomatous pyelonephritis
Craig W D et al. Radiographics 2008;28:255-276
©2008 by Radiological Society of North America

46. Xanthogranulomatous Pyelonephritis
(XGP)
Radiographics. 2000;20:215-243
Radiographics. 2000;20:215-243

47. Xanthogranulomatous Pyelonephritis
(XGP)

Other Findings

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Extrarenal Extension
Nodes
Fistula
Segmental

48. Tuberculosis

Pathophysiology





Renal cortical
deposition occurs in
primary infection
Reactivation (one
kidney) in medulla
Descending process
Destruction, fibrosis,
calcification,
obstruction
Dx

Culture (sterile pyuria)

49. Tuberculosis

KUB
Diffuse or scattered
renal calcifications
(25%)
 Often small renal
shadow
 “putty kidney”

Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

50. Tuberculosis

CTU (IVP)

Renal






Ureter





Moth eaten, fuzzy calyx with
papillary necrosis
Infundibular, pelvic fibrosis (purse
string pelvis)
Calyceal/pelvic obstruction
(hydrocalyx, phantom calyx)
Renal nonfunction
(autonephrectomy), scarring
calcification (putty kidney)
Note: renal changes mimic TCC
Ulcerations and irregularity;
sawtooth (early)
Multiple strictures; corkscrew
(later)
Short, strait, aperistaltic (latest)
Calcifications (DDX:
schistosomiasis)
Bladder involvement is very late
AJR 2005; 184:143-150

51. Renal Parenchyma Malakoplakia
(RPM)


Inflammatory condition to chronic E. coli infection
Disordered macrophage response to bacterial
phagocytosis


Entire GU tract can be affected



histologic hallmark is basophilic inclusions (MichaelisGutmann bodies) within large eosinophilic macrophages (von
Hansemann histiocytes)
Most commonly urothelial plaques (bladder esp.)
RPM occurs uncommonly
Usually middle age women with h/o chronic infection

Flank pain, fever

52. Renal Parenchyma Malakoplakia
(RPM)

Findings:
Bilateralor unilateral
 Focal, multifocal or
diffuse
 infiltrating masses
 Renal pelvis
involvement may
occur
 Calcifications
uncommon

Radiographics. 2000;20:215-243.)

53. Fungal Disease




Usually immunocompromised
(DM, steroids, HIV, etc.)
Candida most common
Any portion of urinary tract
Imaging


Changes of PN, abscess
Fungus ball in collecting system

Non-stone (echogenic) filling
defect

DDX: sloughed papilla, tcc, clot
Kawashima A - Infect Dis Clin North Am - 01-JUN-2003

54. Outline








Pyelonephritis
Renal Abscess
Emphasematous Pyelonephritis
Pyonephrosis
Xanthogranulomatous Pyelonephritis
TB
Renal Malakoplakia
Other Infection