[Rapid growth of glioblastoma during therapy for multiple myeloma: case report].

Rapid growth of a glioblastoma during therapy for multiple myeloma is reported. A 53-year-old man was admitted to our hospital with a right costal tumor, which was resected. The diagnosis was plasmocytoma. Urine protein electrophoresis showed a monoclonal peak in the region of gamma-globulin, and examination of the bone marrow revealed 17.8% of atypical plasma cells. Brain magnetic resonance (MR) imaging detected two small lesions, but these could not be identified as brain tumor. He received chemotherapy (melphalan 10 mg/day and predonin 30 mg/day for 4 days) and was discharged. Two weeks after discharge, he was readmitted because of left hemiparesis. T1-weighted MR imaging showed two large hypointense lesions in the right frontal lobe, with ring-like enhancement following Gd-DTPA infusion. 1H-MR spectroscopy showed typical findings of tumor with increased choline and lactic acid peaks. 201Tl SPECT revealed high accumulation in both early and delayed images. Right carotid angiography showed a hypervascular tumor with venous filling and mass effect. The lesions were resected via right frontal craniotomy, followed by intraoperative radiation and placement of an Ommaya reservoir. Histological examination showed the tumors were glioblastoma. The brain between the tumors also showed the typical appearance of glioblastoma, suggesting that the lesions were continuous. Postoperatively, the patient's left hemiparesis disappeared. He received local irradiation and chemotherapy and was then discharged. Coexistence of glioblastoma and multiple myeloma is rare. The cause may be genetic abnormality, but immunodeficiency due to multiple myeloma, surgical damage, or chemotherapy may have contributed to the rapid growth of the glioblastoma.