Bence Jones type multiple myeloma showing diffuse infiltration to the dura mater by myeloma cells

: A 62-year-old man with aleukemic Bence Jones type multiple myeloma who developed neurologic abnormalities is reported. After admission, consciousness disturbance appeared and a lumbar puncture obtained M-protein. Though brain CT showed no abnormal findings except a punched out lesion of the temporal bone, MRI disclosed remarkable enhancement of the dura mater. Meningeal involvement by myeloma cells without leukemic blood picture is very rare though it is common in other lymphoproliferative disorders such as acute lymphocyte leukemia and malignant lymphoma. We report a case of BJ type multiple myeloma with meningeal involvement due to diffuse infiltration to the dura mater and discuss a possible mechanism of meningeal involvement in this patient.