Cytokeratin Positivity in Meningiomas: Clinical Implications and Association with Tumor Progression

Objectives The clinical application of evidence on genetic and epigenetic mechanisms of meningioma recurrence and malignant progression is limited. In this study, we aimed to evaluate whether cytokeratin immunohistochemistry (IHC) could serve as a surrogate marker reflecting tumor progression in meningiomas. Materials and Methods Cytokeratin IHC using CAM5.2 and AE1/AE3 antibodies was performed in samples obtained from 24 meningioma cases. For statistical analyses, CAM5.2-based scoring (C-score) was used. Clinicopathological features were analyzed, particularly in reoperated cases. Statistical Analysis Cases were dichotomized into low- and high-expression groups according to the C-score, using a cutoff value of 2 (0-1 vs. 2-6). The Kaplan-Meier analysis and Fisher's exact test were performed in the cohort with World Health Organization (WHO) grade I tumors at initial surgery. Results Complete negativity for both CAM5.2 and AE1/AE3 was observed in four cases. Among the nine reoperated cases, six showed grade change. C-scores were stable or increased over time in all reoperated cases. The Kaplan-Meier analysis showed a significant difference in event-free survival between the low- and high-expression groups (log-rank p = 0.0342; Wilcoxon p = 0.0356). Fisher's exact test in the same cohort showed no significant association between C-score group and grade change. Conclusion Cytokeratin IHC, particularly when assessed using CAM5.2-based scoring, may serve as a practical surrogate marker of tumor progression in meningiomas. Further validation in larger cohorts with longer follow-up is warranted.