Leptomeningeal relapse of multiple myeloma following allogeneic stem cell transplantation.

Progressive multiple myeloma may manifest features of 'de-differentiation', including a plasmablastic appearance, failure to secrete paraprotein, extramedullary involvement, and resistance to treatment. A 44-year-old woman with kappa-light chain myeloma underwent allogeneic stem cell transplantation (SCT). Twenty months later she developed paraspinal plasmablastic myeloma in the absence of paraprotein in urine or myeloma in the marrow. The paraspinal masses responded to chemotherapy. At 30 months she developed myelomatous meningitis, which proved resistant to intrathecal chemotherapy, irradiation, and donor lymphocyte infusion (DLI). The leptomeningeal disease led to death at 38 months. This is the first report of leptomeningeal relapse of myeloma after allografting.