Some advances in the field of physico-chemical characterization of pathological microcrystals.

Recent advances in the characterization of microcrystals in tissue samples based on physico-chemical techniques are reviewed. It is a new opportunity for the physician to access early a diagnosis of rare but severe pathologies and to start a specific therapy able to delay or to stop an irreversible alteration of the organ, for example to avoid dialysis and transplantation when kidney is mainly affected. To date, more than 400 biopsies of kidneys containing crystals were performed and characterized using such techniques. The data collected on crystals, tissue alteration, clinical and biological investigations are of prime importance to help a better understanding of biochemical process involved in crystal formation. Such techniques may be applied to microcrystalline pathologies affecting other organs than kidney, namely prostate, pancreas, thyroid, breast… Multicentric and international collaborations were developed, thus offering new opportunities in studying pathophysiology of deposited microcrystals and their consequences. In fact, crystals may be the consequence of various pathologies, but they are also involved in the dysfunction of the tissue where they accumulate. Two techniques are mainly applied to such diagnosis: scanning electron microscopy and Fourier transform infrared spectroscopy, including synchrotron radiation infrared microspectroscopy.