Waldenström's macroglobulinemia and nephrotic syndrome with membranous nephropathy

Area of Science:

• Nephrology
• Hematology
• Immunology

Background:

• Renal complications in Waldenström's macroglobulinemia (WM) are uncommon.
• Nephrotic syndrome associated with WM is typically secondary to amyloidosis.
• This report focuses on a rare presentation of WM with nephrotic syndrome.

Observation:

• A 44-year-old male with a 4-year history of WM presented with significant proteinuria (7.8 g/24 h).
• Kidney biopsy findings included mesangial expansion, thickened capillary loops, and epimembranous spikes.
• Immunofluorescence revealed strong IgM and λ chain deposition, with weaker C3 and C1q staining.

Findings:

• The patient was diagnosed with membranous nephropathy characterized by immunoglobulin M (IgM) deposition, a rare cause of nephrotic syndrome in WM.
• Treatment targeting WM with rituximab and fludarabine, along with an angiotensin receptor blocker, led to reduced serum IgM, serum viscosity, and proteinuria.
• Proteinuria improved from 7.8 g/24 h to 4.8 g/24 h, and renal function remained stable with creatinine at 1 mg/dL.

Implications:

• This case highlights membranous nephropathy with IgM deposition as a treatable cause of nephrotic syndrome in Waldenström's macroglobulinemia.
• Effective management of the underlying WM is crucial for improving renal outcomes.
• Early diagnosis and integrated treatment strategies can lead to significant renal recovery and sustained function.