Multiple myeloma associated with a 9S IgG paraprotein and carcinoma of the prostate

A case of multiple myeloma associated with a 9S IgG complex. kappa‐type light chains, and adenocarcinoma of the prostate is described. The relative amount of 9S globulin was independent of total protein concentration; it was the predominant M‐component in both highly diluted serum and also in whole serum. At low pH, it was dissociated to the 7S monomer. The presence of moderately high concentrations of the 9S species in the patient's serum did not cause symptoms of the hyperviscosity syndrome. A review of the literature suggests that the association of myeloma with nonreticular neoplasms may occur more often than previously supposed.