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Bladder

Cystitis

Malakoplakia


Reviewer: Monika Roychowdhury, M.D., University of Minnesota Medical Center (see Reviewers page)
Revised: 26 April 2011, last major update April 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● 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 tumors; often misdiagnosed clinically as a malignant condition

Terminology
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● 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
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● More common in immunocompromised (HIV, renal transplant recipients) and women
● Mean age at diagnosis is fifth decade
● Rare in children

Etiology
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● 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
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● Patients usually present with urinary symptoms and urinary tract infection (72% due to E. coli)
● Rarely associated with calcified plaques (encrusted cystitis, Ir J Med Sci 2006;175:74) and renal failure (Nat Clin Pract Urol 2008;5:516)

Case reports
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● 12 year old girl with urinary and gastrointestinal malakoplakia (Urology 2009;73:87)
● 18 year old man with malakoplakia of bladder and ureter (Cases J 2009 May 29;2:7527)
● 76 year old woman with hematuria (Case of the Week #131)

Treatment
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● 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

Gross description
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● Multiple 3-4 mm soft yellow plaques or nodular thickenings of bladder wall near trigone with peripheral hyperemia resembling carcinoma

Gross images
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Malakoplakia

Micro description
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● Can be divided in 3 stages initial inflammatory stage, classic stage with abundant Michaelis-Gutmann bodies and 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)

Micro images
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Malakoplakia (arrows at Michaelis-Gutmann bodies)

               
Case of the Week #131

   
Case of the Week #131: Left - von Kossa stain, Right - iron stain


Plaque-like lesion eroding the bladder mucosa

           
At higher magnification, the target-shaped Michaelis-Gutmann bodies (arrows) are prominent

   
von Kossa calcium stain


CD68

Electron microscopy
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● Macrophages have phagosomes that are packed with undigested bacterial products

End of Bladder > Cystitis > Malakoplakia


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