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Rinsho Ketsueki. 1990 Oct;31(10):1740-4.

[A long-term observation of development from monoclonal gammopathy of undetermined significance (MGUS) into primary amyloidosis].

[Article in Japanese]

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Department of Internal Medicine, Faculty of Medicine, Kyoto University.


The term, "monoclonal gammopathy of undetermined significance (MGUS)" is used because it is not known at the time of recognition whether the M-component will remain stable or will develop into multiple myeloma (MM) or related disorders. Recently, we have encountered a case of MGUS in which a diagnosis of primary amyloidosis (PA) was made more than 10 years after the recognition of an M-component in the serum. A 64-year-old man presented in 1979 for evaluation of monoclonal gammopathy. The level of M-component (IgG-lambda) in the serum was 1.6 g/dl. The urinary Bence Jones proteins (BJP) were negative. Bone marrow aspirate contained 9.8% plasma cells. Skeletal surveys were normal. A diagnosis of MGUS was made. In 1982, a trace amount of BJP was detected in the urine. Since 1988, carpal tunnel syndrome, angina pectoris and congestive heart failure developed in succession. In November 1989, the patient was admitted to Kyoto University Hospital for examination. Serum electrophoretic pattern remained unchanged. The excreted amount of urinary BJP was less than 0.3 g/day. Bone marrow aspirate contained 5.4% plasma cells. Histologic studies of bone marrow biopsy specimens revealed amyloid deposition. An echocardiogram was thought to reveal amyloidosis. Significant uptake of Tc-99m (V) DMSA was found in carpal regions, kidneys and heart. A diagnosis of PA was made. It is noteworthy that the development of PA did not accompany an increase in the serum M-component. An early diagnosis of PA as well as MM should be kept in mind in the follow-up study of patients with MGUS.

[Indexed for MEDLINE]

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