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Kidney non-tumor

Tubular and interstitial diseases

Malakoplakia


Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 25 December 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Also spelled malacoplakia
● Foamy macrophages with PAS+ granular cytoplasm and Michaelis-Gutmann bodies (may be due to deposition of amorphous salts, Am J Surg Pathol 1984;8:151)
● Associated with transplants
● May be due to defective macrophage function that blocks lysosomal degradation of engulfed bacteria, filling up cytoplasm with undigested debris

Case reports
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● 65 year old woman with malakoplakia of kidney extending to descending colon (Korean J Fam Med 2011;32:367)

Gross description
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● Soft, yellow mucosal plaques

Gross images
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55 year old man with recurrent urinary tract infections

Micro description
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● Foamy macrophages with PAS+ granular cytoplasm due to phagosomes stuffed with bacterial debris and Michaelis-Gutmann bodies (laminated mineralized concretions)
● May have rare Michaelis-Gutmann bodies, late fibrous stage (Am J Surg Pathol 1989;13:225)

Micro images
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Various images


55 year old man with recurrent urinary tract infections

Positive stains
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● Calcium (von Kossa), iron (Prussian blue)

Electron microscopy description
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● Intracellular calcific inclusions

Electron microscopy images
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Tongue mass: A-Michaelis-Gutman body has electron-dense core surrounded by granular amorphous osmophilic protein; B-macrophage shows multiple intracellular electron-dense bacillary forms within a large vacuole (asterisk); small Michaelis-Gutman body is seen in an adjacent macrophage (arrow)

Differential diagnosis
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Xanthogranulomatous pyelonephritis: no Michaelis-Gutmann bodies

End of Kidney non-tumor > Tubular and interstitial diseases > Malakoplakia

Ref Updated: 8/21/12


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