A 76-year-old woman with newly diagnosed lambda light chain myeloma was found to have involvement of the pleura and meninges. Direct immunofluorescence demonstrated the monoclonal nature of plasma cells found in the pleural fluid; morphologically similar cells were found in the cerebrospinal fluid and bone marrow. Immunoelectrophoresis revealed lambda light chains in the pleural fluid and cerebrospinal fluid, as well as in the serum and urine. Clinically apparent pleural involvement and meningeal involvement by myeloma are each rare events. This is believed to be the first report of both phenomena occurring simultaneously and the first known case of light chain myeloma involving the cerebrospinal fluid.
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