[Clinical and morphological findings and problems in malacoplakia of the urinary bladder (author's transl)]

Malacoplakia of the urinary bladder (observations on 4 female patients, average age 47 years, longest duration 8 years) is, under light microscopy, arranged in 4 layers. Zone 1 contains inflammatory granulation tissue. Zone 2 is composed of von Hansemann cells (macrophages). In zone 3, Michaelis-Gutmann bodies appear. Finally, the deepest zone 4 contains connective tissue, blood vessels, and lymphoplasmacellular infiltrates. By electron microscopy, the gradual formation of residual bodies from the remains of phagocytosed materials in the macrophages in these layers can be observed. Through loading with calcium and iron compounds, the residual bodies take on the characteristic appearance of Michaelis-Gutmann bodies. Etiologically, the origin of malacoplakia is probably involved with coliform bacteria, but apparently additional factors are required for the development of a disease process: e.g., disturbance of macrophage function. There are certain parallels between malacoplakia and Whipple's disease. With atypical localization outside the urinary bladder, differential diagnostic difficulties can arise in separating malacoplakia from inflammatory-granulomatous processes (granulomatous orchitis, xanthogranulomatous pyelonephritis). The prognosis of malacoplakia in the urinary bladder is good in all cases, but timely treatment of recurrence and constant supervision are indicated.