Primary systemic amyloidosis.

Abstract

Primary amyloidosis is a plasma cell dyscrasia in which insoluble immunoglobulin light chain fragments are produced and polymerize into fibrils that deposit extracellularly, causing visceral organ dysfunction and death. The disorder is rare. Its recognition requires understanding the association between nephrotic syndrome, cardiomyopathy, peripheral neuropathy, and hepatomegaly with amyloidosis. The most important screening test for amyloidosis is immunofixation of the serum and urine to detect a monoclonal immunoglobulin light chain. All patients need the diagnosis confirmed histologically. The least invasive source of tissue for amyloid detection is the subcutaneous fat. The most important prognostic factor is whether there is cardiac involvement, which is best assessed by echocardiography with Doppler studies. Therapies used include oral melphalan/prednisone and high-dose corticosteroids. High-dose chemotherapy followed by stem cell reconstitution seems to provide the highest reported response rates. Transplant is associated with unique morbidities not seen in the transplantation of patients with other hematologic malignancies.