Malakoplakia Outside the Urinary Tract

Abstract Context.—Malakoplakia is a rare granulomatous disease that occurs commonly in the urinary tract. Histologically, it is defined by sheets of histiocytes (Hansemann cells) with accumulation of granular basophilic periodic acid-Schiff– positive, diastase-resistant inclusions and calcified Michaelis-Gutmann bodies, which are pathognomonic but not necessary for diagnosis. In addition to the urinary tract, malakoplakia has been reported in other organs, including the gastrointestinal tract, central nervous system, female genital tract, and the tongue. Objectives.—To review the literature of reported sites of malakoplakia outside the urinary tract and their variable clinical presentations, and to discuss the main diagnostic features and differential diagnoses of malakoplakia. The pathogenesis and possible etiologic factors are also presented. Data Sources.—Data for this work were collected from the published literature, textbooks, and the Internet. Conclusions.—It is important to be aware of the existen...