Concurrent Unilateral Temporal Glioma and Contralateral Temporal Arachnoid Cyst: Case Series and Review of Literature

ABSTRACT: Arachnoid cysts are benign, congenital, cerebrospinal fluid-filled lesions, most often located in the middle cranial fossa, and usually discovered incidentally. Gliomas, in contrast, are the most common primary brain tumors of glial origin. The coexistence of dual intracranial pathologies is rare, and when reported, typically involves arachnoid cysts associated with other congenital or vascular abnormalities. To date, there are no published reports describing the coexistence of a glioma with a contralateral arachnoid cyst. We present two cases of concurrent unilateral temporal glioma with contralateral temporal arachnoid cyst. The first case involved a 15-year-old male with focal seizures and headaches, whose MRI revealed a left temporal ganglioglioma and a large right temporal arachnoid cyst. He underwent gross total excision of the tumor and cysto-cisternostomy of the arachnoid cyst, with histopathology confirming pilocytic astrocytoma. The second case involved a 45-year-old male with headaches and seizures, whose imaging demonstrated a right temporal oligodendroglioma and a contralateral left temporal arachnoid cyst. He underwent right temporal craniotomy and tumor excision with decompression of the arachnoid cyst, with histology confirming oligodendroglioma, IDH mutant, WHO grade 2. Both patients had uneventful postoperative recoveries. This is the first reported series of concurrent unilateral temporal glioma and contralateral arachnoid cyst. Although the coexistence may be incidental, a possible developmental or structural predisposition cannot be excluded. Careful radiological evaluation is essential to distinguish and appropriately manage both lesions.