Paraneoplastic minimal change nephropathy: a diagnostic challenge.

INTRODUCTION

Myeloma-associated glomerulopathy could mimic idiopathic minimal change nephropathy, which poses a diagnostic challenge to nephrologists.

CASE REPORT: A 60-year-old patient presented with nephrotic range of proteinuria. Serum creatinine level was normal. Immune markers and tumor markers were unrevealing. No monoclonal protein was detected on serum protein electrophoresis. Renal biopsy showed marked effacement of foot processes and no evidence of immunoglobulin or amyloid deposition on electron microscopy/immunofluorescence staining, compatible with idiopathic minimal change nephropathy histologically. However, proteinuria persisted despite steroid treatment. In view of the atypical course of the disease, workup for secondary glomerulopathy was repeated and paraproteinuria was unexpectedly found. Subsequent bone marrow examination confirmed light chain myeloma.

CONCLUSION

Urine protein electrophoresis and serum/urine immunofixation are useful tests to detect the monoclonal protein in suspicious cases.