An unusual case of supraclavicular and colonic malakoplakia--a light and ultrastructural study.

A case of malakoplakia of the supraclavicular region and colon in a 41-year-old patient is presented. Clinical, histopathological, histochemical and ultrastructural features are described. The etiology and pathogenesis are discussed. Malakoplakia is a chronic inflammatory disorder probably due to an abnormal response to infection with Gram negative bacteria, most likely Escherichia coli or Klebsiella. The disease is characterised by the accumulation of macrophages intermixed with plasma cells and lymphocytes. The malakoplakic cells are laden with phagolysosomes which may provide a suitable biochemical environment for the deposition of calcium to form the pathognomonic Michaelis-Gutmann bodies. Ultrastructural examination enhances the accuracy of diagnosis since it highlights the presence of lysosomes, phagolysosomes, Michaelis-Gutmann bodies, and intact E. coli or their remnants.