Intraoperative integrated diagnostic system for malignant central nervous system tumors.

The 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors uses an integrated approach involving histopathology and molecular profiling. Since majority of adult malignant brain tumors are gliomas and primary central nervous system lymphomas (PCNSL), rapid differentiation of these diseases is required for therapeutic decisions. Additionally, diffuse gliomas require molecular information on single nucleotide variants (SNV), such as IDH1/2. Here, we report an intraoperative integrated diagnostic (i-ID) system to classify CNS malignant tumors, which updates legacy frozen section (FS) diagnosis through incorporation of a quantitative polymerase chain reaction (qPCR)-based genotyping assay. FS evaluation, including GFAP and CD20 rapid immunohistochemistry, was performed on adult malignant CNS tumors. PCNSL was diagnosed through positive CD20 and negative GFAP immunostaining. For suspected glioma, genotyping for IDH1/2, TERT SNV, and CDKN2A copy number alteration was routinely performed, whereas H3F3A and BRAF SNV were assessed for selected cases. i-ID was determined based on the 2021 WHO classification and compared with the permanent integrated diagnosis (p-ID) to assess its reliability. After retrospectively analyzing 153 cases, 101 cases were prospectively examined using the i-ID system. Assessment of IDH1/2, TERT, H3F3AK27M, BRAFV600E, and CDKN2A alterations with i-ID and permanent genomic analysis was concordant in 100%, 100%, 100%, 100%, and 96.4%, respectively. Combination with FS and intraoperative genotyping assay improved diagnostic accuracy in gliomas. Overall, i-ID matched with p-ID in 80/82 (97.6%) patientswith glioma and 18/19 (94.7%) with PCNSL. The i-ID system provides reliable integrated diagnosis of adult malignant CNS tumors.