Changing concepts in pathogenesis and morphology of analgesic nephropathy as seen in Europe.

A detailed analysis of 60 autopsy cases of AN is presented. Renal papillary necrosis is the hallmark of AN. Special emphasis is given to early changes in the basement membranes and the ground substance of the renal papilla observed by light and electron microscopy. The "interstitial nephritis" in the renal cortex is secondary to papillary changes. The histologic picture of the cotex is often complicated by bacterial infection and, therefore, is complex. An unusual hyalinization of small vessels beneath the urothelium of the mucosa of the urinary tract, similar to that seen in the inner medullary zone, has been called "analgesic microangiopathy". Its significance is not clear. The renal papillae, the mucosal membranes of the urinary tract, the liver, the cartilages, and the skin often display a striking brownish discoloration caused by a lipid-containing pigment. Statistical data from out autopsies in Switzerland show no decrease in death rates of AN. This is in contrast to reports from Denmark and Sweden where the sale of phenacetin has been restricted by prescription.