We sought to review outcomes of patients who have immunoglobulin light-chain amyloidosis of the IgM type. Fifty patients with a serum IgM monoclonal protein and biopsy-proven amyloid were evaluated. The percentages of patients presenting with cardiac, renal, hepatic, and pulmonary amyloid were 44%, 32%, 14%, and 10%, respectively. Forty-two percent had an M-protein spike in the serum greater than 1.5 g/dL, and 14% had an IgM peak greater than 3 g/dL. Amyloidosis was diagnosed easily by biopsies of the subcutaneous fat, rectum, and bone marrow, which demonstrated deposits in 84%, 72%, and 50%, respectively. The median survival of all patients was 24.6 months. Fifty-three percent of all deaths were due to cardiac amyloidosis. Twelve percent died of respiratory failure, and 7% each died of macroglobulinemia, hepatic failure, and renal failure. Of the 22 patients with amyloid cardiomyopathy, the median survival was 11.1 months and fewer than 10% survived 5 years. Of the 28 patients without amyloid cardiomyopathy at diagnosis, the median survival was 27 months, with approximately 30% surviving 5 years. We conclude that the presence of amyloid cardiomyopathy and an increased creatinine concentration had the greatest impact on survival.
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