Immunoglobulin light chain amyloidosis: 2013 update on diagnosis, prognosis, and treatment

Abstract

Immunoglobulin (Ig) light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of Ig light chain are deposited in tissues. Clinical features depend on organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, peripheral/autonomic neuropathy, and atypical multiple myeloma. Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow biopsy or subcutaneous fat aspirate in 85% of patients. Verification that amyloid is of immunoglobulin origin is mandatory. N-terminal pro-brain natriuretic peptide (NT-proBNP), serum troponin T, and immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months. All patients with a visceral amyloid syndrome require therapy to prevent deposition of amyloid in other viscera and prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include NT-proBNP <5,000 ng/mL, troponin T < 0.06 ng/mL, age <70 years, <3 organs involved, and serum creatinine ≤1.7 mg/dL. Nontransplant candidates can be offered melphalan-dexamethasone. Pomalidomide appears to have activity, as do other combinations of chemotherapy with agents such as cyclophosphamide-thalidomide (or lenalidomide or bortezomib)-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide. Late diagnosis remains a major obstacle to initiating effective therapy when organ dysfunction is still recoverable. Recognizing the presenting syndromes is necessary for improving survival.