Rapid polymer-based immunohistochemistry for intraoperative CNS tumor diagnosis: A validation study

Intraoperative diagnostics in neuro-oncology face a critical gap between the morphological limitations of hematoxylin-eosin staining or toluidine blue staining and the time-intensive nature of conventional immunohistochemistry (IHC). This delay hinders real-time surgical decision-making, particularly in distinguishing gliomas, metastases, and lymphomas. To address this, we validated a novel, rapid IHC protocol utilizing directly conjugated polymerized horseradish peroxidase (pHRP) antibodies, designed to deliver results in under 30 minutes. We evaluated the performance of pan-cytokeratin (pan-CK), glial fibrillary acidic protein (GFAP), and cluster of differentiation 20 (CD20) antibodies on 115 intraoperative frozen tissue samples. Staining quality was assessed using a 4-tiered scoring system (from 0 to 3+). The cytoplasmic markers GFAP and pan-CK demonstrated excellent robustness and reliability, achieving mean scores of 2.6 and 2.47, respectively, with over 68% of cases showing strong, specific staining (3+). The membrane-bound marker CD20 showed more variability (mean score 2.07), highlighting the influence of antigen localization on this rapid protocol. Our findings demonstrate that this rapid IHC method is a viable and highly effective tool for the intraoperative differentiation of central nervous system tumors, particularly for cytoplasmic antigens. By providing crucial morphological information in near real-time, this approach has the potential to significantly enhance diagnostic precision during surgery, enabling immediate, tailored therapeutic strategies and improving patient outcomes.