Conclusion: Diagnosis of ISCM in both cases without preoperative signs of neoplasm in other organs was surprising. Immunohistochemical analysis was essential for determination of cancer origin. Objective: Tetraspanin CD151 is a positive effector of cancer invasion and metastasis in many tumor types. Method: We investigated the protein expression of CD151 in 211 cases of WHO grade I to IV gliomas. Additionally, we performed O6-methylguanin-DNA methyltransferase (MGMT) methylation analysis using real-time methylation-specific PCR in 36 glioblastomas, and the prognostic significance of these biomarkers in glioblastomas was evaluated.