Light chain disease: report of an atypical case.

A 50-year-old black man had the signs and symptoms of severe anemia. His bone marrow contained sheets of primitive cells that could only be conclusively identified as being of plasmacytic origin by electron microscopy. These cells produced only a small quantity of kappa light chain but did fluoresce when stained with immunofluorescent antikappa stain. His initial response to chemotherapy was dramatic, but after eight months his condition was refractory to all further attempts at treatment. This case supports the observation of Hobbs that patients with Bence-Jones myeloma may have a poorer prognosis than those with otherwise typical IgG or IgA myeloma.