Crystalline deposits of calcium and phosphorus: their appearance in glomerular basement membranes in a patient with renal failure.

The kidneys and lungs of a 71-year-old man with a 30-month history of biopsy-proven Wegener's granulomatosis were examined at autopsy. They displayed striking crystalline deposits in glomerular basement membrane (GBM) and, to a much lesser extent, other basement membranes. The patient had been in renal failure, with peritoneal dialysis instituted three weeks before death. Energy-dispersive x-ray microanalysis of these deposits showed them to consist of calcium and phosphorus. Transmission electron microscopy revealed their presence diffusely throughout all layers of GBMs, with focal areas showing early reactive membrane formation. Control studies confirmed these deposits as being an endogenous, in vivo phenomenon, representing a morphologic finding not previously described to our knowledge.