X-ray microanalysis of the Michaelis-Gutmann bodies of malakoplakia.

The Michaelis-Gutmann (MG) inclusion bodies of three cases of malakoplakia (prostate, testis, colon) were studied by X-ray microanalysis to determine their elemental composition. Calcium and phosphorus were consistently found. Iron was detected in a few bodies. No other elements were detected. The electrondense laminations were of similar composition to the core material. Small aggregates of electron-dense material containing calcium and phosphorus were also occasionally seen in phagolysosomes. These observations are consistent with view that MG bodies arise by a process of phagolysosomal coalescence and mineralisation.