"Secondary" plasma-cell dyscrasia: a plea for change in terminology, with an illustrative case report.

The demonstration of monoclonal, homogeneous immunoglobulin or its subunit is the hallmark of plasma-cell dyscrasia. Plasma-cell dyscrasia can be classified into two main groups: "primary" and "secondary". The increasing use of protein electrophoresis and immunoelectrophoresis has contributed to the increased frequency of secondary monoclonal gammopathy and to the better recognition of its clinical significance. Secondary monoclonal gammopathy usually stems from the reactive unbalanced proliferation of B cells resulting from chronic inflammatory diseases or from other malignancies. Only in some cases its cause is difficult to assert. A case of secondary plasma-cell dyscrasia of undetermined cause is presented. The patient had IgG kappa monoclonal gammopathy of 3580 mg/dl, and multiple osteolytic bone lesions. However the histopathological picture showed a chronic inflammatory process, and the diagnosis of multiple myeloma could not be established. The diagnostic problems in this case are discussed, with the recommendation that more strict and accurate immunochemical terms concerning monoclonal gammopathy be used.