RESUMEN
A 67-year-old male was admitted to the hospital for evaluation of incidentally detected anemia and mild azotemia. Urinalysis showed no abnormal finding and 24 hr urine protein amount was clinically insignificant (270 mg/day). Urine and serum protein electrophoresis were negative for a monoclonal spike. However, urine and serum immunoelectrophoresis demonstrated the presence of monoclonal free kappa light chains. Renal biopsy showed the features of chronic tubulointerstitial disease and on the immunofluorescence studies, kappa light chain was in a linear pattern in basement membranes of glomeruli and tubules. Work-up for multiple myeloma including bone marrow biopsy showed results compatible with multiple myeloma. Treatment was started with vincristine, adriamycin and doxorubicin at monthly interval for three months followed by autologus peripheral blood stem cell transplantation. At follow-up 5 months after autologus peripheral blood stem cell transplantation, the patient is well with a serum creatinine of 2.3-2.6 mg/dL and 24 hr urine protein of 200-350 mg.