Bladder, ureter & renal pelvis

Other nonneoplastic

Malakoplakia



Topic Completed: 1 March 2015

Minor changes: 11 November 2021

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PubMed Search: Malakoplakia [title] bladder

Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Malakoplakia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladdermalakoplakia.html. Accessed December 8th, 2021.
Definition / general
  • Rare histiocytic disease that occurs in all organs
  • Common in GU tract, particularly bladder
  • Also gastrointestinal tract (most commonly colon, followed by stomach and duodenum), central nervous system, female genital tract (Radiographics 2006;26:1847)
  • Single or multiple white-yellow soft raised plaques on the mucosal surface
  • Often misdiagnosed clinically as a malignant condition
Terminology
  • First described by Michaelis and Gutmann in 1902 and later named by Von Hansseman
  • "Malakoplakia" comes from Greek words malakos (soft) and plakos (plaque)
Epidemiology
  • More common in immunocompromised (HIV, renal transplant recipients) and women
  • Mean age at diagnosis is fifth decade
  • Rare in children
Etiology
  • Caused by defects in phagocytic or degradative functions of histiocytes in response to gram negative coliforms (E. coli or Proteus) that results in chronic inflammatory state, followed by intracellular deposition of iron and calcium (known as Michaelis-Gutmann bodies)
Clinical features
Case reports
Treatment
  • Antibiotics that concentrate in macrophages (quinolones or trimethoprim-sulfamethoxazole), antibiotics directed against E. coli plus surgery
  • Possibly bethanechol (may correct decreased cGMP levels that may interfere with complete bacterial killing, eMedicine)
  • Discontinuation of immunosuppressive drug therapy
Clinical images

Contributed by Zachary Gordon, M.D., G. Bailey, M.D. and the Genitourinary Pathology Society (Case #496)

White light cystoscopy


Narrow band cystoscopy

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Cystoscopic view of bladder lesions

Microscopic (histologic) description
  • Can be divided in 3 stages:
    • Initial inflammatory stage
    • Classic stage with abundant Michaelis-Gutmann bodies
    • Third stage with progressive fibrous tissue and scarring
  • Foamy epithelioid histiocytes with PAS+ granular eosinophilic cytoplasm in lamina propria, some lymphocytes and occasional giant cells
  • Histiocytes have increased number of phagosomes containing non-digested bacteria (usually E. coli or Proteus), contain Michaelis-Gutmann bodies (iron containing, cytoplasmic laminated mineralized concretions)
Microscopic (histologic) images

Contributed by Cheng Wang, M.D. and the Genitourinary Pathology Society (Case #496)
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Various images

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PAS stain

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Von Kossa stain




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Malakoplakia (arrows at Michaelis-Gutmann bodies)


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von Kossa calcium stain

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CD68

Virtual slides

Images hosted on other servers:
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Bladder malakoplakia

Electron microscopy description
  • Macrophages have phagosomes that are packed with undigested bacterial products
Board review style question #1
What is the name of the targetoid bodies, which are pathognomonic for malakoplakia?

  1. Asbestos bodies
  2. Aschoff bodies
  3. Howell-Jolly bodies
  4. Michaelis-Gutman bodies
  5. Psammoma bodies
Board review style answer #1
D. Michaelis-Gutman bodies

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Reference: Malakoplakia
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