[A case of multiple myeloma with intracerebral metastasis]

Compared to leukemia, malignant lymphoma and other hematogenous tumors, multiple myeloma rarely metastasizes to the central nervous system. Intracerebral metastasis without involvement of the cranium itself is rarer. We report a case of Ig-G k-type multiple myeloma with metastasis to the left frontal lobe extending to the right basal ganglia without involvement of the cranium. A 71-year-old male complained of exertional dyspnea and lumbago. His laboratory data revealed hyperproteinemia and an abnormal increase in Ig-G (6117mg/dl) in his serum. Serum protein immunoelectrophoresis revealed an IgG k-type band, and Bence-Jones protein was detected in his urine. MMPP, VMCP, VIPP and MP chemotherapy was given, and serum IgG level decreased to a normal range. 21 months after his first admission, incontinence, disorientation, gait disturbance and apathy developed. CT-scan showed an isodense lesion with massive edema in the left frontal lobe and right basal ganglia. On MRI, a Gd-DTPA enhancing lesion was detected extending from the left frontal to the opposite frontal lobe through the splenium. No abnormal skull punched out lesions were noted. Left frontal lobectomy was performed. Histopathology revealed plasmablastic myeloma cells with clear nucleole and eccentric nucleus in the cerebrum. He was diagnosed as having intracerebral metastasis of multiple myeloma without involvement of the cranium. Unfortunately, he died of pancytopenia and pneumonia. Our case suggests the possibility of metastasis via blood into the cerebrum.