Boron neutron capture therapy for recurrent malignant meningioma. Case report.

Malignant meningioma is a rare brain tumor with a high risk of recurrence. If this tumor recurs after complete resection and adjuvant radiotherapy, there is no optimal treatment to control it. The authors report the first case of recurrent malignant meningioma treated using boron neutron capture therapy (BNCT). This 25-year-old pregnant woman presented with a large frontal tumor. After her baby was born, she underwent gross-total resection of the tumor. A second resection and three Gamma Knife surgeries could not control progression of the enhancing mass; therefore, the authors applied BNCT based on their experience with it in the treatment of malignant gliomas. The minimum tumor dose and maximum brain tissue dose were estimated as 39.7 Gy-Eq and less than 9.0 Gy-Eq, respectively. Before BNCT the patient was mobile by wheelchair only, whereas 1 week after therapy she was able to walk. Twenty-two weeks later she underwent a second BNCT for tumor regrowth on the contralateral side, and the lesion was subsequently reduced. The tumor volume was markedly decreased from 65.6 cm3 at the time of the first BNCT to 31.8 cm3 at 26 weeks thereafter. The treatment of recurrent malignant meningioma is difficult and has been discouraging thus far. Data in the present case indicate that BNCT may be a promising treatment option for this challenging tumor.