Is it appropriate to redefine the indication for stereotactic brain biopsy in the MRI Era? Correlation with final histological diagnosis in supratentorial gliomas.

BACKGROUND: The aim of this study was to evaluate the advisability of modifying the indications for stereotactic brain biopsy (SBB) in high- and low-grade supratentorial glial tumors in correlation with the diagnostic accuracy of magnetic resonance imaging (MRI).

MATERIALS AND METHODS: We analyzed 174 cases of supratentorial glial lesions diagnosed by MRI before biopsy. On the basis of the MRI findings the patients were divided into two groups: high-grade (n=107) and low-grade (n=67) gliomas. All patients underwent CT-guided biopsy. Only one preoperative diagnosis was allowed.

RESULTS: A final histological diagnosis was achieved in 95% of the 174 cases. In the group of high-grade gliomas (HGG) there was diagnostic coincidence in 87% of cases, reaching 100% in lesions of the corpus callosum. In 11 cases (10%) the histological analysis changed the presumptive diagnosis and the consequent management. In the group of low-grade gliomas (LGG) there was diagnostic coincidence in 63% (42 cases), whereas there was discordance in 30%: 10 cases were upgraded to anaplastic astrocytoma, and in 10 cases no tumors were observed at all.

CONCLUSIONS: In the future, the histological diagnosis of glial tumors will include molecular genetic definition, thus making it crucial for management using the new therapeutic options. Today, the indications for biopsy in lesions mimicking high-grade gliomas are mainly linked to the site of the tumor, coexisting differential diagnoses or more than one treatment option. In lesions of the corpus callosum, histological analysis seems not to be required in order to proceed to complementary therapies. On the contrary, in lesions where MRI findings indicate low-grade gliomas, grading is crucial also in order to avoid treatment inappropriate in non-neoplastic lesions.