ABSTRACT
The crystal deposition is constituted of biological apatites. However, ectopic calcifications are also observed and may represent severe injuries for the patient. Ectopic calcifications, most periarticular, articular, dental, or visceral, are essentially constituted of calcium phosphate, as opposed to the calculi. The variability of the inorganic phase of ectopic calcifications explains the extensive and uncoordinated literature on the subject. Biological examinations are needed to diagnose a general pathology favoring metastatic calcifications. During acute crisis, there is a biological inflammatory syndrome. Pathological study shows deposits of calcific ma-terial surrounded by necrosis and inflammatory cells. Calcified tissues are fixed in ethanol to avoid demineralization, and are embedded in methyl methacrylate. X-ray radiographs of shoulder periarticular calcification can reveal enormous calcification in the bursa, with or without destructive arthropathy, associated with numerous “apatite-like” precipitations. The role of ions of biological interest, like Mg, must be determined, due to their suspected role in calcification and crystal maturation.
