Renal disease related to Waldenström macroglobulinaemia: incidence, pathology and clinical outcomes.

The incidence and prognostic impact of nephropathy related to Waldenström macroglobulinaemia (WM) is currently unknown. We performed a retrospective study to assess biopsy-confirmed WM-related nephropathy in a cohort of 1391 WM patients seen at a single academic institution. A total of 44 cases were identified, the estimated cumulative incidence was 5·1% at 15 years. There was a wide variation in kidney pathology, some directly related to the WM: amyloidosis (n = 11, 25%), monoclonal-IgM deposition disease/cryoglobulinaemia (n = 10, 23%), lymphoplasmacytic lymphoma infiltration (n = 8, 18%), light-chain deposition disease (n = 4, 9%) and light-chain cast nephropathy (n = 4, 9%), and some probably related to the WM: thrombotic microangiopathy (TMA) (n = 3, 7%), minimal change disease (n = 2, 5%), membranous nephropathy (n = 1, 2%) and crystal-storing tubulopathy (n = 1, 2%). The median overall survival in patients with biopsy-confirmed WM-related nephropathy was 11·5 years, shorter than for the rest of the cohort (16 years, P = 0·03). Survival was better in patients with stable or improved renal function after treatment (P = 0·05). Based on these findings, monitoring for renal disease in WM patients should be considered and a kidney biopsy pursued in those presenting with otherwise unexplained renal failure and/or nephrotic syndrome.