Rapid immunohistochemistry for intraoperative differentiation between high-grade gliomas and primary central nervous...

Rapid intraoperative differentiation between high-grade gliomas (HGGs) and primary central nervous system lymphomas (PCNSLs) is critical because surgical strategies and adjuvant therapies differ substantially. We conducted a multicenter prospective observational study to evaluate rapid immunohistochemistry (R-IHC) on frozen sections using alternating current electric field mixing. Forty-eight adults with newly suspected malignant intra-axial brain tumors underwent tumor resection or biopsy with intraoperative frozen section consultation. The prespecified primary endpoint was antibody level concordance between R-IHC and conventional immunohistochemistry on permanent formalin-fixed, paraffin-embedded sections. Intraoperative diagnostic performance using hematoxylin and eosin (HE) alone versus HE plus R-IHC was assessed descriptively. Final diagnoses were HGG in 37 patients, PCNSL in 8, and other lesions in 3. For HGG, HE-based intraoperative diagnosis showed 91.9% sensitivity and 90.9% specificity, whereas HE plus R-IHC showed 100% sensitivity in this cohort and unchanged specificity (90.9%). CD20 showed complete concordance between rapid and permanent staining. Ki-67 labeling indices were strongly correlated between the two methods (Spearman r = 0.821). Therefore, R-IHC provides reliable immunostaining results on frozen sections and may serve as a practical adjunct to HE-based intraoperative differentiation between HGGs and PCNSLs in this diagnostic setting.