A patient with malacoplakia of the urinary bladder may present with a number of clinical findings and pathologic findings.


The patient may be asymptomatic, or may have:

(1) a febrile illness, including FUO

(2) recurrent urinary tract infections

(3) hematuria

(4) bladder irritability (frequency, urgency, etc)

(5) renal insufficiency


Cystoscopy shows soft, yellowish brown plaques or nodules (malacoplakia = "soft plaque") with peripheral hyperemia. Chronic lesions may become firm or ulcerated.


The biopsy shows chronic granulomatous inflammation with histiocytes. Giant cells and well-formed granulomas are uncommon. The characteristic feature is the Michaelis-Gutmann body which may be intracellular or extracellular. These range from 2-10 microns in diameter and have a target-like appearance. These stain positively with several stains including PAS or Prussian blue stains.


On electron microscopy the Michaelis-Gutmann bodies are mineralized phagosomes containing partially digested bacteria.


A false negative histologic diagnosis may occur if the Michaelis-Gutman bodies are absent, which may occur in very early or long-standing lesions.


Differential diagnosis:

(1) bladder tumors

(2) tuberculosis

(3) sarcoidosis


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