KIDNEY INVOLVEMENT IN IDIOPATHIC LIGHT CHAIN DISEASE. REPORT OF ONE CASE Idiopathic Light Chain disease (ILCD) is a systemic disease characterized by a deposit in different organs of light chain monoclonal immunoglobulins, produced by an abnormal clone of B cells. It is usually found in the course of a plasma cell dyscrasia and in other lymphoproliferative alterations; however it may occur in absence of any hematologic disease and is denominated as idiopathic. We report a 51 years old male admitted to the hospital due to anasarca. Laboratory evaluation showed a serum creatinine of 1.4 mg/dl, a serum albumin of 1.6 g/dl, a serum cholesterol of 687 mg/dl and a proteinuria of 5.3 g/day. Light chains with a predominance of a monoclonal component were identified in urinary proteins by electrophoresis and kappa chains were identified by immunofixation. A renal biopsy showed a diffuse nodular glomerulopathy with a 35% tubular atrophy and interstitial sclerosis. Electron microscopy confirmed light chain deposition. The bone marrow biopsy showed a myeloid hyperplasia. The patient was initially treated with methylprednisolone and plasmapheresis with a reduction in serum creatinine and disappearance of urinary kappa component. Albuminuria persisted and a malnutrition-inflammatory complex syndrome was diagnosed. Hemodialysis with ultrafiltration was started along with cyclophosphamide. The patient received hemodialysis for six months and continued with methylprednisolone.