Waldenström-like lymphoma with monoclonal IgG1-kappa: evidence of common clonal origin.

A patient with a pleomorphic lymphoplasmacytic bone marrow infiltration, a peripheral lymphocytosis and a monoclonal IgG1-kappa gammopathy is described. An antiidiotype serum, raised against the monoclonal serum protein showed a common clonal origin of the pleomorphic cell population. In the light of recent report on B-cell neoplasms associated with M-components, a hypothetical scheme of the cellular clonal event is proposed.