[Light chain deposition disease].

We report the case of a rather rare form of K-light chain deposition disease (LCDD) in a 61-year-old man with hypertension and rapidly progressing nephropathy. Laboratory findings prompted suspicion of the diagnosis which was confirmed by light-microscopic and immunofluorescent studies of samples taken by percutaneous renal and liver biopsy. Hepatic and urinary K-light chains were present; no circulating light chains were detected. Bone marrow examination evidenced mild infiltration of lymphoid cells, all positive for K-light chain staining. Plasma cells were within normal ranges. LCDD appeared as nodular glomerulosclerosis with rare crescents and extensive tubular involvement with K-light chain deposits. There was no evidence of altered liver function, nor was amyloid found in the bone marrow, kidney or liver. After one year of continuous therapy with melphalan and prednisone, the patient's renal function has not worsened. We conclude with a review of the clinical and physiopathological features of the light chain subgroup of monoclonal immunoglobulin deposition diseases (MIDD).