"Myeloma Protein" in a Patient with Monocytic Leukemia

A 74 year old man with monocytic leukemia was found to have serum and urinary protein findings typical of myelomatosis. Lysozyme excretion in the urine was in the range characteristic of monocytic leukemia. There were no x-ray findings indicative of myeloma. Aspirated bone marrow specimens contained one to three per cent plasma cells, and less than 0.1 per cent atypical plasma cells. The leukemia responded temporarily but without remission to treatment with 6MP and steroid, with no effect on the myeloma protein profile or excretion of the urinary proteins.

The leukemia was present without overt morphologic or x-ray findings of myeloma, and the case differs from a similar example of the association of myeloma protein with monocytic leukemia in which the leukemia occurred as a terminal event in a previously well-documented myelomatosis.

The serum contained a fast-moving "myeloma gamma globulin" which was classified as γ-1, Kappa; Gm. (a + b - f -) Inv. (a). This protein was heterogeneous by starch gel electrophoresis. The urine contained large amounts of lysozyme, Fab, Fc and F'c fragments of the "myeloma gamma globulin," light chains of type Kappa, as well as whole gamma globulin. Small amounts of other serum proteins were also found.

The possibility of two neoplastic proliferations involving both the monocytes and plasma cells has been considered. Possible role of monocytoid stem cells with giant nucleoli in the synthesis of "myeloma protein" has been discussed.