Improving diagnostic accuracy and interobserver concordance in the classification and grading of primary gliomas

The authors' data indicate that oligodendroglial tumors comprise up to 25% of gliomas, a significantly higher proportion than was previously recognized. The data also suggest that the wide range of survival times reported for patients with anaplastic astrocytoma may reflect "contamination" resulting from misdiagnosis, particularly of oligodendroglial tumors and pilocytic astrocytomas.