Intracranial Chondroma beyond the Skull Base: A Two-Case Series Including an Unusual Presentation with Cerebrospinal Fluid (CSF) Leak and Encephalocele

Background: Intracranial chondromas are rare, benign cartilaginous tumors typically arising from the skull base. The convexity location is exceptionally uncommon and can mimic more common extra-axial lesions such as meningioma, leading to diagnostic challenges. Methods: A prospective maintained university medical center registry was utilized to undertake a retrospective review of patients operated with convexity chondroma. Clinical presentation, imaging findings, surgical approach and histopathology were analyzed. A review of literature, particularly concerning atypical presentations such as Cerebrospinal Fluid (CSF) leak, was also conducted. Results: Both patients underwent successful gross total resection with no perioperative complications or tumor recurrence. One patient presented with a large lesion measured 11 cm in maximum diameter, with stable outcome and recurrence-free at 12-month follow-up. The second patient, a lesion measured 5 cm and was resected and has remained, during 12 years follow-up, stable clinical and radiologically with no recurrence. A CSF leak with associated encephalocele occurred in one case and was managed effectively using an endoscopic endonasal repair in a second operation. Conclusion: Although rare, convexity intracranial chondromas should be included in the differential diagnosis of extra-axial masses. Optimal outcomes rely on high clinical suspicion and a multidisciplinary approach. These cases illustrate that gross total resection can provide control of these kind tumor, regardless of the size, with excellent long-term outcomes. Clinical significance lies in recognizing that even giant lesions can behave indolently if they are resected completely, emphasizing the importance of accurate diagnosis, multidisciplinary surgical approach, planning and long-term follow-up.