Pathology of the Kidney in Waldenström's Macroglobulinemia

Renal function, proteinuria and renal histology, including five biopsies and 13 autopsies, were studied in 16 patients with Waldenström's macroglobulinemia. Glomerular abnormalities included amyloidosis in three cases and in six cases the presence of striking deposits, located on the endothelial aspect of the basement membrane, sometimes so voluminous as to occlude the capillary lumen, resembling thrombi. Immunofluorescent analysis of these deposits or thrombi suggested that they contained exclusively lgM. The morphologic aspect, as well as the composition, of these deposits may indicate a passive deposition of circulating lgM that is perhaps due to hyperviscosity. Interstitial infiltration, found in 10 cases, was of the same type as that observed in the bone marrow. In contrast to patients with myeloma, tubular casts with macrophagic reaction were never detected.