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
