Oligodendroglial neoplasms: Current concepts, misconceptions, and folklore

Given current prognostic and therapeutic implications, the accurate classification and grading of oligodendroglial neoplasms has become critical. However, the prevalence of morphologically ambiguous gliomas, subjective histologic criteria, personal biases, oligodendroglioma mimics, and the lack of specific oligodendroglioma markers has led to high interobserver variability and created a contentious problem encountered daily in active surgical neuropathology practices. Since histologic assessment is still a powerful prognosticator, it appropriately remains the diagnostic gold standard. However, recent efforts have focused on identifying the most reproducible and clinically relevant criteria, standardizing classification and grading: schemes, and searching for useful ancillary biologic and genetic markers capable of further stratifying an otherwise heterogenous patient population. This paper reviews the morphologic and genetic spectrum of oligodendroglial neoplasms, recent diagnostic and prognostic developments, and potential future directions.