Preferential recurrence of a sarcomatous component of a gliosarcoma after boron neutron capture therapy: case report.

Gliosarcoma, a rare pathological entity composed of 2-8% malignant gliomas, is characterized by a biphasic tissue pattern with alternating areas displaying glial and mesenchymal differentiation. Here we report the preferential recurrence of a sarcomatous component in gliosarcoma after boron neutron capture therapy (BNCT), while a gliomatous component disappeared as a result of the treatment. A 56-year-old woman with a left frontal tumor was introduced to our clinic. After stereotactic biopsy, craniotomy was applied and 90% of the mass was resected. The histological diagnosis was glioblastoma with small amounts of sarcomatous component, that is, gliosarcoma. BNCT was applied 30 days after craniotomy. Two weeks after BNCT, almost all of the contrast-enhanced mass had disappeared on magnetic resonance images; however, a half year later, the mass recurred just below the original site and extended posteriorly. Irrespective of repetitive salvage surgeries, the patient died of the recurrent tumor. At autopsy, tumor cells of the frontal lobe were absent. A well-circumscribed mass of the parietal and occipital lobes was composed of sarcomatous material, with very little glial fibrillary acid protein-positive glial material. We found in this patient the preferential recurrence of the sarcomatous component of a gliosarcoma after potent radiotherapeutics in the form of BNCT.