Worsening Proteinuria Reveals Lymphoplasmacytic Lymphoma

Introduction: A patient presented with worsening proteinuria diagnosed as Lymphoplasmacytic Lymphoma (LPL). Chemotherapy treatment was effective, significantly improving proteinuria and IgM levels Case Description: A 59-year-old male with chronic lymphocytic lymphoma (CLL), Diabetes presented with new nephrotic range proteinuria of 3172 mg/g microalbumin/creatinine ratio from baseline of around 600, new foamy urine and creatinine elevation from 0.8 to 1 mg/dL. Further tests revealed elevated IgM (1243), kappa/lambda free light chain ratio (9.35), hypercalcemia, and IgM kappa spike (0.61 g/dL). Bone marrow biopsy showed a 30-40% cellular infiltrate of small lymphocytes. Kidney biopsy was pursued due to unexplained worsening proteinuria which revealed mild mesangial expansion with patchy dense mononuclear inflammatory infiltrates predominantly small lymphocytes (CD20+ve) with scattered plasma cells (figure 1), consistent with LPL. After 2 cycles of Rituximab-bendamustine, urine protein/creatinine ratio improved from 1.23 to 0.62; IgM level decreased to 327, M spike to 0.13 g/dL, creatinine back to baseline and urine appearance normalized. Discussion: This case highlights the importance of proteinuria surveillance, especially in patients with CLL. Any changes in proteinuria should be aggressively investigated while other management strategies are pursued. A low threshold for kidney biopsy is crucial, as timely intervention can help preserve kidney function. Further research is essential to deepen our understanding of the pathogenesis and potential connections between CLL and LPL. While these conditions are distinct entities, cases of their co-occurrence have been documented. Investigating these associations more thoroughly could offer valuable insights into the mechanisms of disease and therapeutic strategies.Figure 1