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Bladder, ureter & renal pelvis

Other nonneoplastic

Malakoplakia

Author: Monika Roychowdhury, M.D.

Last author update: 1 March 2015

Last staff update: 29 March 2023 (update in progress)

Copyright: 2003-2023, PathologyOutlines.com, Inc.

PubMed Search: Malakoplakia [title] bladder

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Table of Contents

Cite this page: Roychowdhury M. Malakoplakia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladdermalakoplakia.html. Accessed April 1st, 2023.

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

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

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)
Woman in her early 50s with multiple broad based bladder mucosal lesions (Case of the Week #496)

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

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)