Tumors of the central nervous system are potentially curable. For tumors of comparable histology and grade, resectability is the most important prognostic factor affecting survival particularly in children. However, the infiltrative nature of the malignant cells produces indistinct borders between normal and malignant tissues, and the lack of easily identifiable tumor margins confounds attempts toward total resection. The investigators propose to identify the borders of tumors intraoperatively using protoporphyrin fluorescence of the malignant cells and thereby provide more complete tumor resection.