Implications of DNA methylation classification in diagnosing ependymoma

Background Ependymoma is a central nervous system tumor that arises from the ependymal cells of the brain's ventricles and spinal cord. The histopathology of ependymomas is indistinguishable regardless of the site of origin, and the prognosis varies. Recent studies have revealed that the development site and prognosis reflect the genetic background. In this study, we used genome-wide DNA methylation array analysis to investigate the epigenetic background of ependymomas from different locations treated at our hospital. Methods Four cases of posterior fossa ependymomas and 11 cases of spinal ependymomas were analyzed. Results DNA methylation profiling using the DKFZ methylation classifier showed that the methylation diagnoses of the two cases differed from the histopathological diagnoses, and two cases could not be classified. Tumor that spread from the brain to the spinal cord was molecularly distinguishable from other primary spinal tumors. Conclusions Although adding DNA methylation classification to conventional diagnostic methods may be helpful, the diagnosis in some cases remains undetermined. This may affect decision-making regarding treatment strategies and follow-up. Further investigations are required to improve the diagnostic accuracy of these tumors.