American Urological Association - Malakoplakia

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Home Education Educational Programs E-Learning Pathology for Urologists Urinary Bladder Non-Neoplastic Lesions Malakoplakia

Malakoplakia

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Image B

  • Most often seen in women (75%) and peak at 50's to 70's.
  • Due to defective bactericidal capacity of histiocytes, as a result, ingested bacteria become calcified and laminated forming distinctive inclusions.
  • Usually caused by Escherichia coli and other gram-negative bacteria.
  • Most common in bladder trigone, and may occur in other parts of GU tract.
  • By cystoscopy, visible as single or multiple soft yellow or yellow-brown mucosal plaques ("malakos" = soft; "plakus" = plaques) (image A).
  • Histology:
    • Accumulation of histiocytes with pale pink foamy cytoplasm (von Hansemann histiocytes)
      (image B).
    • Diagnostic feature is the presence of intracytoplasmic round concentric basophilic inclusions (Michaelis-Guttman bodies).
    • Michaelis-Guttman bodies can be highlighted by PAS, von Kossa or iron stains.

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