Nephrotic syndrome caused by protein thrombi in glomerulocapillary lumen in Waldenström's macroglobulinaemia

Waldenström's macroglobulinaemia (WM) is described as a disorder of plasmacytoid lymphocytes. The renal complications of WM are less common and severe than those of multiple myeloma. We present a case of WM complicated by nephrotic syndrome. A biopsy specimen of the kidney revealed the intraglomerular thrombi of immunoglobulin M paraprotein. Corticosteroid pulse therapy and plasmapheresis were effective in improving proteinuria and reducing protein thrombi. The nephrotic syndrome caused by protein thrombi in WM may be reversible, at least in its early stage.