Kidney nontumor / medical renal


Chronic pyelonephritis

Last author update: 10 July 2023
Last staff update: 10 July 2023

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PubMed Search: Chronic pyelonephritis

Saman Karimi, M.D., M.S.
Suman Setty, M.B.B.S., Ph.D.
Page views in 2023: 24,457
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Cite this page: Karimi S, Setty S. Chronic pyelonephritis. website. Accessed February 23rd, 2024.
Definition / general
  • Diffuse, patchy tubulointerstitial inflammation and scarring accompanied by blunting of calyces and the renal pelvis
Essential features
  • Chronic pyelonephritis
ICD coding
  • ICD-10:
    • N11.0 - nonobstructive reflux associated chronic pyelonephritis
    • N11.1 - chronic obstructive pyelonephritis
  • Renal parenchyma
  • Reflux of urine and ascending infection into the renal pelvis
  • Obstructive uropathy
  • Vesicoureteral reflux
  • Chronic inflammation and infection leading to deformed and atrophic calyces with fibrosis and scarring of the renal parenchyma
  • Recurrent damage and scarring leads to renal insufficiency and end stage renal disease (ESRD)
  • Complicated chronic pyelonephritis is associated with nephrolithiasis
  • Most common bacterial organism associated with chronic pyelonephritis: Escherichia coli
  • Reference: Am J Physiol Renal Physiol 2017;312:F43, Radiol Med 2021;126:505, Am J Kidney Dis 2016;68:e23, Nephrol Dial Transplant 2006;21:1423
Diagrams / tables

Contributed by Saman Karimi, M.D., M.S., Suman Setty, M.B.B.S., Ph.D. and Vijay Shankar, M.D.
Schematic of Chronic Pyelonephritis Schematic of Chronic Pyelonephritis

Schematic of chronic pyelonephritis

Clinical features
  • Elevated blood urea nitrogen (BUN) and elevated serum creatinine
  • Urinalysis: proteinuria, renal epithelial cells, granular casts, pyuria (acute on chronic, recurrent acute pyelonephritis)
Radiology description
  • Focal, polar, coarse cortical scars, calyceal distortion and renal atrophy
  • Hypertrophy of residual renal parenchyma, mimicking infarct on imaging
  • Ureteral dilation if severe reflux disease is present
  • Obstruction with calculi may be present in obstructive nephropathy
  • References: Emerg Radiol 2020;27:561, Radiographics 2008;28:255
Prognostic factors
Case reports
  • Surgical intervention: correction of anatomic / congenital abnormalities resulting in reflux
  • Medical management: antimicrobial therapy for treatment of recurrent, acute pyelonephritis
  • Long term antibiotic prophylaxis with trimethoprim / sulfamethoxazole, trimethoprim, nitrofurantoin, among others
  • In pediatric patients who develop end stage renal disease due to reflux, transplant is a treatment modality
  • References: Tunis Med 2018;96:495, Porter: The Merck Manual of Diagnosis and Therapy, 20th Edition, 2018
Microscopic (histologic) description
  • Patchy interstitial lymphoplasmacytic inflammation with occasional, focal neutrophilic infiltration
  • Patchy, well demarcated scarring of the renal pelvis and calyces
  • Abundant intraluminal Tamm-Horsfall protein casts
  • Tubular atrophy with thyroid type tubular atrophy and interstitial and periglomerular fibrosis
  • Secondary segmental glomerulosclerosis
  • References: Niger Postgrad Med J 2020;27:37, Yale J Biol Med 1985;58:91, Am J Kidney Dis 2016;68:e23
Microscopic (histologic) images

Contributed by Saman Karimi, M.D., M.S. and Suman Setty, M.B.B.S., Ph.D.
Renal cortical parenchyma with tubular atrophy and interstitial fibrosis, Masson Trichrome special stain

Interstitial chronic
tubular atrophy
and fibrosis

Interstitial chronic inflammation and periglomerular fibrosis

Interstitial chronic
inflammation and
periglomerular fibrosis

Renal tubular atrophy with luminal casts

Renal tubular atrophy with luminal casts

Renal tubular atrophy with luminal casts

Dense interstitial fibrosis

Virtual slides

Images hosted on other servers:

Xanthogranulomatous pyelonephritis

Electron microscopy description
  • No specific findings

Overview of chronic pyelonephritis

Histological features of chronic pyelonephritis

Sample pathology report
  • Kidney, radical nephrectomy:
    • Renal cortical thinning with blunted calyces and scarring
    • Global glomerulosclerosis with marked tubular atrophy and thyroid type tubular atrophy of the renal tubules
    • Diffuse interstitial lymphoplasmacytic infiltration
    • These findings are consistent with chronic pyelonephritis
Differential diagnosis
Board review style question #1

A 79 year old man presented with benign prostatic hyperplasia, obstructive uropathy and lobular segmental hypertrophy of the left kidney. A nephrectomy is performed revealing the histology above. What is the most likely diagnosis?

  1. Acute pyelonephritis
  2. Chronic pyelonephritis
  3. Diabetic nephropathy
  4. Emphysematous pyelonephritis
  5. Xanthogranulomatous pyelonephritis
Board review style answer #1
B. Chronic pyelonephritis. The image shown above illustrates atrophic tubules with luminal casts, diffuse interstitial lymphoplasmacytic infiltration, interstitial fibrosis and globally sclerosed glomeruli. The most likely histologic diagnosis is chronic pyelonephritis.

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Reference: Chronic pyelonephritis
Board review style question #2
Which of the following histologic features are associated with chronic pyelonephritis?

  1. Glomerular cellular crescents with segmental necrotizing change
  2. Histiocytes with granular eosinophilic cytoplasm and Michaelis-Guttman bodies
  3. Interstitial dense neutrophilic inflammation and tubular luminal neutrophils
  4. Tubular atrophy and luminal casts; interstitial lymphoplasmacytic inflammation and fibrosis
Board review style answer #2
D. Tubular atrophy and luminal casts; interstitial lymphoplasmacytic inflammation and fibrosis

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Reference: Chronic pyelonephritis
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