Immunoglobulin light chain amyloidosis: 2012 update on diagnosis, prognosis, and treatment

Disease Overview: Immunoglobulin (Ig) light chain amyloidosis is a clonal but nonproliferative plasma cell disorder in which fragments of an Ig light chain are deposited in tissues. The clinical features depend on the organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, and peripheral/autonomic neuropathy. Diagnosis: 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. Prognosis: N-terminal pro-brain natriuretic peptide and serum troponin T values are used to classify patients into three groups of approximately equal size; median survivals are 26.4, 10.5, and 3.5 months, respectively. Therapy: All patients with a visceral amyloid syndrome require therapy to prevent deposition of amyloid in other viscera and to prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is a preferred technique, but only 20% of patients are eligible. Requirements for safe SCT include mild or no cardiac involvement, troponin T value <0.06 ng/mL, age <70 years, <3 organs involved, and serum creatinine value ≤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-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide. Future Challenges: Late diagnosis remains a major obstacle to initiating effective therapy when organ dysfunction is still recoverable. Recognizing the presenting syndromes is necessary for improvement in survival.