Bladder & urothelial tract

Other nonneoplastic

Malakoplakia


Editorial Board Member: Michelle R. Downes, M.D.
Mustafa Goksel, M.D.

Last staff update: 16 May 2024 (update in progress)

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed Search: Malakoplakia

Mustafa Goksel, M.D.
Page views in 2023: 1
Page views in 2024 to date: 9,427
Cite this page: Goksel M. Malakoplakia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladdermalakoplakia.html. Accessed May 19th, 2024.
Definition / general
  • Chronic inflammatory disorder that affects many organs, most commonly occurs in urinary bladder
  • Single or multiple white-yellow soft raised plaques on the mucosal surface, can mimic malignancy (Nephrourol Mon 2014;6:e18522)
Essential features
  • Histiocytic infiltrate with characteristic cytoplasmic basophilic inclusions
  • Round histiocytes (von Hansemann cells) and rounded, concentric, basophilic, cytoplasmic inclusion (Michaelis-Gutmann bodies)
  • Mass forming, typically polypoid bladder mass with intact mucosa
Terminology
ICD coding
  • ICD-10
    • N32.8 - other specified disorders of bladder
    • N28.8 - other specified disorders of kidney and ureter
    • N36.8 - other specified disorders of urethra
  • ICD-11
    • GC01.Y - other specified disorders of bladder
    • GB90.Y - other specified disorders of kidney or ureter
    • GC0Y - other diseases of urinary system
Epidemiology
  • More common in immunocompromised patients, patients with diabetes mellitus, renal transplantation recipients (Arch Ital Urol Androl 2022;94:350)
  • Prevalence: 4 times higher in women
  • Mostly affects people over 40 years old
Sites
Pathophysiology
  • Thought to be a defect in macrophage phagolysosomal response to bacterial infection, resulting in accumulation of macrophages with calcified inclusions composed of undigested bacteria and products (Am J Kidney Dis 2016;68:e27)
Etiology
  • Exact etiology unknown
  • Recurrent urinary infections (E. coli and other gram negative bacilli) and immunosupression
Clinical features
Diagnosis
  • Histological by biopsy
Case reports
  • 55 year old woman with history of kidney disease presented with general malaise and worsening renal failure and was found to have a bladder mass (Pathol Res Pract 2022;237:153852)
  • 61 year old immunocompromised man with symptoms of urinary obstruction was found to have exuberant malakoplakia of prostate presenting as prostatic abscess (J Endourol Case Rep 2020;6:231)
  • 82 year old woman with intravesical malakoplakia mimicking an aggressive transitional cell carcinoma (Bladder (San Franc) 2020;7:e44)
Treatment
  • Antibiotics or surgical excision
Clinical images

Contributed by Zachary Gordon, M.D.

White light cystoscopy

Narrow band cystoscopy

Microscopic (histologic) description
  • Sheets of histiocytes with granular eosinophilic cytoplasm (von Hansemann cells) and basophilic intracytoplasmic inclusion (Michaelis-Gutmann bodies)
Microscopic (histologic) images

Contributed by Mustafa Goksel, M.D.
Sheets of eosinophilic histiocytes

Sheets of eosinophilic histiocytes

Urinary bladder with histiocytic infiltration

Urinary bladder with histiocytic infiltration

Numerous intracytoplasmic inclusions

Numerous intracytoplasmic inclusions

Von Kossa stain Von Kossa stain

Von Kossa stain

Von Kossa stain

Von Kossa stain

Negative stains
Sample pathology report
  • Bladder lesions, biopsy:
    • Benign urothelial mucosa with acute and chronic inflammation and prominent histiocytic infiltrate, consistent with malakoplakia (see comment)
    • Comment: Special stains for von Kossa (calcium) were performed on block A1 and highlight concentrically layered basophilic inclusions (Michaelis-Gutmann bodies), supporting the diagnosis of malakoplakia.

  • Bladder lesions, biopsy:
    • Malakoplakia
Differential diagnosis
Board review style question #1
What is the name of the targetoid bodies that are pathognomonic for malakoplakia?

  1. Asbestos bodies
  2. Aschoff bodies
  3. Howell-Jolly bodies
  4. Michaelis-Gutmann bodies
  5. Psammoma bodies
Board review style answer #1
D. Michaelis-Gutmann bodies are characteristic inclusions seen in many cases of malakoplakia. They are rounded, concentric, intracytoplasmic, basophilic inclusions, caused by accumulation of undigested bacteria and products that are calcified. They can be highlighted by von Kossa stain. Answer A is incorrect because asbestos bodies are golden brown colored and fusiform to beaded rod shaped structures. Answer B is incorrect because Aschoff bodies are microscopic nodules of cells composed of pleomorphic cells, lymphocytes, plasma cells and fibrinoid necrosis. Answer C is incorrect because Howell-Jolly bodies are spherical intracytoplasmic inclusions within red blood cells. Answer E is incorrect because psammoma bodies are a round collection of calcium, a form of calcification that is mostly extracellular and much bigger than an intracellular inclusion.

Comment Here

Reference: Malakoplakia
Board review style question #2

Which of the following stains used in the diagnosis of malakoplakia targets structures shown with yellow arrows in the image above?

  1. CD4
  2. CD68
  3. CD163
  4. Von Kossa
Board review style answer #2
D. Von Kossa. The von Kossa stain highlights the Michaelis-Gutmann bodies in malakoplakia. Answers B and C are incorrect because CD68 and CD163 stains highlight the histiocytes in malakoplakia. Answer A is incorrect because CD4 has no role in the diagnosis of malakoplakia.

Comment Here

Reference: Malakoplakia
Back to top
Image 01 Image 02