Lastly, MTB discussions resulted in 9 (21.4%) cases having a diagnosis change (Table 1), including identification of an entirely new diagnosis (n = 3: from infiltrating glioma to pilocytic astrocytoma; from primitive neuroepithelial tumor to AT/RT; and from CNS embryonal tumor with rhabdoid features to astroblastoma, MN1-altered) or further subclassification (n = 6: identified molecular subgroup in 3 ependymomas and 1 medulloblastoma; 1 infiltrating astrocytoma classified as IDH-mutant and increased grade; and 1 meningioma classified as higher risk based on DNA methylation). The gene discussed is MN1; the disease is pilocytic astrocytoma.