Malakoplakia. Defect in digestion of phagocytized material due to impaired vacuolar acidification?

On the basis of light and electron microscopical findings in a case of malakoplakia of urinary bladder, (1) we concur with others that malakoplakia is a hyperplastic accumulation of histiocytes, and that the formation of Michaelis-Gutmann bodies is associated with incomplete digestion of phagocytized cell debris; (2) we hypothesize that digestion within phagolysosomes is impaired because of deficient acidification; and (3) we suggest that the defect in acidification in some cases may be related to treatment with drugs that affect the mechanism of phagocytic vacuolar acidification.