The etiology of "primary" systemic amyloidosis is not known. The close relationship to multiple myeloma has been pointed out by a number of observers. Thus, Magnus-Levy1 found amyloid deposits in 29 of 150 cases of myeloma he reviewed. He felt that the association of Bence Jones proteinuria and amyloidosis was significant, and that amyloid must be produced by myeloma cells. In instances of "primary" amyloidosis in the absence of tumor cells he believed the amyloid must come from normal plasma cells. Lichtenstein and Jaffe2 suggested that because myeloma is so frequently the basis of "primary" amyloidosis, it should be searched for in every case even though the bones appear normal on x-ray examination or grossly normal at postmortem.
Kyle and Bayrd3 report a study of 81 cases of "primary" systemic amyloidosis seen at the Mayo Clinic during the period from 1935 to 1959. These observers paid particular