A Case Report: Development of Ipsilateral Glioblastoma Multiforme (GBM) in a Patient with a Refractory Epilepsy Due to Bottom-of-Sulcus Dysplasia

Purpose: To report a rare case of ipsilateral IDH-wildtype Glioblastoma (GBM) developing in a male patient with long-standing refractory focal epilepsy attributed to MRI-identified Bottom-Of-Sulcus Dysplasia (BOSD), a subtype of Focal Cortical Dysplasia (FCD). The unique aspect of this case is the sequential occurrence of two anatomically distinct but ipsilateral pathologies. A long-standing MRI-confirmed Bottom-Of-Sulcus Dysplasia (BOSD) causing refractory epilepsy, followed by development of an IDH-wildtype glioblastoma in the ipsilateral hemisphere. Methods: This retrospective case report includes review of the patient’s electronic medical record, epilepsy monitoring unit evaluations, serial brain MRI studies, Stereo-Electroencephalography (SEEG) findings, Responsive Neurostimulation (RNS) device data, operative reports and histopathologic and molecular analyses from tumor resection. Results: A patient with refractory epilepsy due to MRI-identified BOSD in the right posterior mesial frontal lobe, underwent RNS implantation. Seventeen months post-RNS implantation, the patient developed new-onset diffuse headaches and progressive focal deficits. Repeat MRI revealed a new, distinct lesion in the ipsilateral temporal lobe. The new lesion was confirmed by resection and histopathology as IDH-wildtype glioblastoma (WHO Grade 4). Despite multimodal GBM treatment, the patient died 15 months post-GBM diagnosis. Conclusion: This case adds to the limited literature on the sequential pathologies of focal cortical dysplasia and high-grade glioma, particularly highlighting a potential diagnostic challenge when new neurologic symptoms develop in a chronic epilepsy patient which indicates a new pathology. The study emphasizes the importance of continued vigilance, even with a presumed stable epileptogenic lesion. Consequently, avoiding the delay of treatment if clinical status changes.