Konfokale Laserendomikroskopie zur Differenzierung glialer Hirntumore

While the 5th version of the WHO classification of tumors incorporates more genetic markers to determine tumor subtypes, classical histomorphological analysis of glial tumors remains a crucial aspect of tumor grading. As demonstrated in our previous poster, confocal laser endomicroscopes can be used to intraoperatively visualize glial tissue and tissue characteristics such as cellularity, nuclear pleomorphism, glial matrix abnormalities, vascularization and necrosis without the need for processing in a lab or staining. We analyzed how those characteristics can be used to not only determine identify glial tumors, but how they might be used to differentiate low- versus high-grade as well as astrocytic versus oligodendroglial brain tumors.

125 glioma biopsies were harvested and analyzed using a 670 nm confocal laser endomicroscope. They were then examined as hematoxylin and eosin stained frozen sections. All confocal images and frozen sections had previously been analyzed for their tissue characteristics and were now grouped into astroglial and oligodendroglial as well as high- and low-grade tumors. Differences in visualization of these tissue features in astroglial versusoligodendroglial tumors and low-grade versus high-grade tumors were calculated using Fisher"s exact test.

All 125 biopsies were examined successfully. 102 specimens were astroglial, 23 were oligodendoglial. The accuracy for detection of astro- versus oligodendroglial tumors was 90.2 % and 95.7 %, respectively. 42 specimens were low-grade gliomas, 83 specimens were high-grade gliomas. The accuracy for detection of low-grade and high-grade gliomas was 88.1 % and 92.8 %, respectively. Astrocytic tumors showed significantly more nuclear pleomorphism in confocal laser endomicroscopy than oligodendroglial tumors. Necrosis significantly helped in differentiation of low- and high-grade tumors (p

Confocal laser endomicroscopy not only allows identification of glial tumor tissue, but might intraoperatively aid in the further differentiation of glial tumor subgroups. High nuclear pleomorphism is indicative of astrocytic tumors, while the visualization of necrosis points towards high-grade gliomas. All results have to be controlled in a blinded study in the next step.