Light chain deposition disease (LCDD) is a rare disorder caused by deposition of non-amyloid kappa or lambda light chains in various parts of the body. Kappa light chains are involved 80% of the time. The kidneys are always affected, and the heart is affected 80% of the time. Light chain deposition can occur in other organs including the liver, spleen, gut, peripheral nerves, and brain.

The incidence of LCDD is unknown, with the median age of diagnosis being late in the fifth decade. 50%-60% of patients have associated multiple myeloma, and 17% have monoclonal gammopathy of unknown significance (MGUS) or no evidence of plasma cell proliferation. 30%-50% of cases are idiopathic.

Manifestations vary based on the affected organ system, although the kidneys are always involved. Signs and symptoms include proteinuria, hematuria, nephrotic syndrome, hypertension, heart failure, renal failure, arrhythmias, peripheral neuropathy, diarrhea, portal hypertension, liver failure, and dyspnea.

LCDD is pathologically similar to amyloid light chain (AL) amyloidosis, but immunoglobulins do not form amyloid fibrils and do not stain Congo red. Serum and urine protein electrophoresis may not detect a monoclonal protein, but serum free light chain analysis has increased sensitivity. Definitive diagnosis is made with immunohistochemical staining of anti-kappa or anti-lambda light chain antibodies in affected tissue.

Treatment is geared toward controlling the plasma cell disorder and controlling organ dysfunction.