Pyelonephritis
Epidemiology:
- Microorganisms:
- Normal
inhabitants of the intestinal tract:
- Gram
negative bacilli
- E.
coli
- Proteus
- Klebsiella
- Enterobacter
- Streptococcus
faecalis
- Staphylococci
- Other
bacteria
- Fungi
- Viruses
(immunocompromised usually):
- Polyoma virus
- CMV
- Adenovirus
- Pyelonephritis can arise from
ascending from urethra and bladder (most common) or hematogenous
seeding
- Ascending
from urethra:
- Urinary
tract obstruction, congenital or acquired
- Instrumentation
(catheterization usually)
- Vesicoureteral reflux (incompetence
of the vesicoureteral valve):
- Congenital
absence or shortening of the intravesical
portion of the ureter
- Bladder
infection causing decreased ureteral
contractility
- Acquired
vesicoureteral reflux (neurogenic
bladder)
- Bladder
dysfunction (incomplete emptying)
- Urethral
obstruction:
- Neurogenic bladder:
- Diabetes
- Spinal
cord injury
- Diabetes
- Susceptibility
to infection
- Neurogenic bladder
- More
frequent instrumentation
- Immunosuppression and immunodeficiency
- Females
- pregnancy
- Sexual
activity
- Intrarenal reflux (into the
kidney parenchyma):
- Hematogenous infection:
- Ureteral obstruction
- Debilitated
- Immunosuppressed
-
Common sites:
- lower
and upper poles of kidney
- pelvis,
tubules, and interstitium
Gross features:
- acute:
- chronic:
- fibrous
depressions of the cortical surface
- irregular,
asymmetric scarring overlying a dilated, blunted, or deformed calyx
- unilateral
or bilateral
- xanthogranulomatous pyelonephritis:
- may
be confused with RCC clinically, forming large, yellowish orange nodules
Histologic
features:
- acute:
- patchy
interstitial suppurative inflammation
- intratubular neutrophils
- tubular
necrosis
- chronic:
- atrophy
of tubules
- tubules
with atrophy in areas and hypertrophy or dilation in others
- thyroidization – dilated tubules
with flattened epithelium filled with colloid
- interstitial
fibrosis
- fibrosis
in cortex and medulla, and around the calyceal
epithelium
- arcuate and interlobular
vessels with obliterative intimal
sclerosis in the scarred areas
- lymphocytic
infiltrate
- chronic
interstitial inflammation in cortex and medulla, and around the calyceal epithelium
- associated
with inflammation, fibrosis, and deformation of the underlying calyx and
pelvis
- glomeruli usually spared but may
be destroyed in large areas of severe necrosis
- xanthogranulomatous pyelonephritis:
- foamy
macrophages, plasma cells, lymphocytes, PMNs, and occasional giant cells
are present
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
- complications:
- acute:
- papillary
necrosis
- perinephric abscess
- sepsis
-
Other features:
References:
·
Kumar V, Fausto N, Abbas
A. Robbins & Cotran Pathologic Basis of Disease,
Seventh Edition. 7th ed. Saunders; 2004:1552.