[1496] The Pathology of the Border of Glioblastoma Evaluated by 5 Aminolevulinic Fluorescence-Guided Resection

MA Idoate, R Diez Valle, J Echeveste, MD Lozano, A Panizo, JJ Sola. University of Navarra, Pamplona, Navarra, Spain

Background: Gross total resection is increasingly recognized as an important first step and prognostic factor in the treatment of glioblastoma. The removal of the entire MRI enhancing lesion is accepted as the gold standard of gross total resection, although the frequency of verified total resection is suboptimal. Fluorescence-guided resection of glioblastoma using 5 aminolevulinic acid (5-ala) (Gliolan), a fluorescent molecule which is incorporated in tumoral cells before the surgery, is a new surgical technique recently approved. Histopathological characterization of peripheral tumor cells (border zone), including the recently described CD133 positive cells (stem cells) were studied, and correlation with fluorescence was obtained.
Design: Eighteen consecutive glioblastomas, six were recurrent cases, of the same number of patients were resected by 5-ala guided technique. Volumetric MRI measurement was done. A total of 122 biopsies including 65 biopsies from the border of the lesion, as shown by the fluorescence, were studied. A conventional and immunohistochemical study including Ki-67 (Dako) and CD133 (Miltenyi Biotec) by amplification method (Novocastra) was applied. A semiquantitative evaluation of each case was obtained. Appropiate statistical tests were applied.
Results: In all cases, it was seen under the fluorescence three different zones: bright red, predominantly in the center of the tumor and a gradually less intense and non-fluorescent (blue areas) in the periphery. Interestingly, the pink areas always corresponded with atypical tumor cells, never with solid tumor, frequently less atypical than the tumoral cells in the center of the lesion. In general, blue areas corresponded with normal tissue or slight increased cellular density. In border areas, the presence of immunoreactive cells against Ki-67 was considered as tumoral ones. CD133 positive cells were non-observed in the border of tumor. The correlation with the histopathology was excellent: 100% specificity in non-recurrent cases and 94% sensitivity. A 100% resection was achieved as measured by MRI in 7 cases.
Conclusions: Border placed glioblastoma cells as it is identified by 5-ala guided resection are less atypical than the conventional ones, get a low proliferative index and are not immunoreactive against CD133 (stem cells). According to the pathological results, this surgical technique is a very efficient and safe method of achieving maximal safe resection of glioblastoma.
Category: Neuropathology

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 186, Tuesday Morning