Tissue distribution of dialysis amyloidosis.

Twenty-three uremic patients on intermittent hemodialysis for eight to eighteen years provided the material for the present pathological study. In all of them, there was evidence for dialysis related amyloidosis based on previous clinical or histological findings or both. The material examined consisted of nine skin biopsies, five abdominal fat aspirates, eight trans-iliac bone biopsies and numerous post-mortem specimens of various visceral organs from eight cases. None of the skin biopsies or fat aspirates showed amyloid deposits. In only one bone biopsy could a small Congo red positive area be recognized that showed characteristic birefringence under polarizing light. Autopsy material findings were negative except for one case: this patient had been dialyzed for 18 years. Very minute amyloid deposits with a positive immunofluorescence staining for beta 2-microglobulin (beta 2-M) were found in the walls of small vessels from her lung, heart, liver and intestine. Thus, in chronic hemodialysis patients the accumulation of beta 2-M amyloid fibrils in tissues other than joints and juxta-articular structures appears to have a low incidence, to occur lately and to be of limited size. Although extra-articular amyloid deposits may progressively occur and extend with increasing survival time on dialysis, tiny deposits such as those observed in only two of our patients will hardly lead to serious complications.