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Malacoplakia: Pathology, Diagnosis and Treatment

Definition

Malacoplakia is a rare chronic inflammatory, histiocytic, granulomatous disease of the urinary tract, gastrointestinal tract, and other organ systems. It is characterized by whitish-gray, plaque-like mucosal lesions and tumor-like masses.

Epidemiology

Malacoplakia is rare. The urinary bladder is the most common urological site.

Bladder malacoplakia: Cystoscopy shows multiple flat and partly raised, whitish-gray, plaque-like mucosal lesions.

Etiology

Malacoplakia is caused by impaired intraphagosomal bacterial degradation in macrophages in the setting of chronic bacterial infection. The undegraded bacterial remnants serve as a nidus for the formation of intracellular Michaelis-Gutmann bodies (see Pathology). Risk factors for urogenital malacoplakia include chronic urinary tract infection, particularly with E. coli. Other risk factors include immunodeficiency, immunosuppression, malignancy, and other debilitating systemic diseases.

Pathology

Macroscopy

Whitish-gray, plaque-like mucosal lesions, sometimes with a hemorrhagic rim. The lesions become indurated over time because of scarring. The urinary bladder is most commonly affected in women, but any urinary tract organ may be involved.

Histology

Large histiocytes (Hansemann cells) with basophilic intracytoplasmic inclusions (Michaelis-Gutmann bodies) composed of extracellular matrix are pathognomonic.

Signs and Symptoms

• Malacoplakia typically affects patients with chronic bacterial infection and immunosuppression
• Bladder involvement causes dysuria and pollakiuria, and possibly hematuria
• Ureteral involvement may cause hydronephrosis with flank pain or fever
• Renal involvement may cause fever, flank pain, radiological findings suspicious for a mass, or nonspecific symptoms
• Prostatic, testicular, or epididymal involvement may cause pain, swelling, or findings suspicious for a tumor

Diagnostic Workup

The diagnostic workup depends on the site involved and generally proceeds stepwise, using microbiological testing, imaging, and histological confirmation.

Microbiological Testing

Urine sediment and culture; blood culture and serum inflammatory markers as indicated.

Imaging

Ultrasound, abdominal CT, and MRI as indicated.

Endoscopy

Cystoscopy with biopsy, transurethral resection of bladder lesions [cystoscopic appearance of bladder malacoplakia], or ureteroscopy with biopsy.

Treatment

Treatment aims to eradicate the pathogen as completely as possible, correct predisposing factors, and provide surgical treatment when indicated.

Long-Term Antibiotic Therapy

Antibiotic selection should be guided by culture and susceptibility testing whenever possible. Agents with good intracellular penetration are preferred. The optimal treatment duration has not been established; published case series often report courses lasting several weeks. Agents used include fluoroquinolones, trimethoprim-sulfamethoxazole, rifampin, sulfonamides, and doxycycline.

Surgical Treatment

Resection of bladder lesions, ureteral stenting or nephrostomy for obstruction, and nephrectomy for a nonfunctional involved kidney or when malignancy is suspected.

Prognosis

Patients with bladder malacoplakia or unilateral renal involvement have a good prognosis after appropriate treatment. Bilateral renal involvement, transplant involvement, concomitant sepsis, or severe underlying disease is associated with a worse prognosis and increased mortality.

References

Dasgupta u.a. 1999 DASGUPTA, P. ; WOMACK, C. ; TURNER, A. G. ; BLACKFORD, H. N.: Malacoplakia: von Hansemann’s disease.
In: BJU Int
84 (1999), Nr. 4, S. 464–9

Dalla-Palma und Pozzi-Mucelli 2000 DALLA-PALMA, L. ; POZZI-MUCELLI, F.: [The imaging of chronic renal infections].
In: Radiologe
40 (2000), Nr. 6, S. 537–46

  Deutsche Version: Malakoplakie

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