Large Parenchymal Perianeurysmal Cyst: A Case Report.

Parenchymal perianeurysmal cysts are rare. We report a case of 50-year-old woman who presented with persistent headaches and episodes of vomiting for the last 2 months. Magnetic resonance imaging of the brain showed a well-defined solitary cystic lesion with a mural nodule measuring 5.4 × 5.2 × 4.6 cm in the right basifrontal region. The mural nodule was cortically based. It was hypointense on T2-weighted fluid-attenuated inversion recovery and showed intense contrast enhancement with few nonenhancing areas-no evidence of diffusion restriction. The cyst wall was nonenhancing, and magnetic resonance angiogram was unremarkable. Differential diagnoses included intra-axial gliomas such as ganglioglioma and pleomorphic xanthoastrocytoma. Right pterional craniotomy and a transcortical approach were made. Subtotal excision of cyst and clipping of right middle cerebral artery bifurcation thrombosed aneurysm were done. After 6 months of follow-up, patient is stable without any deficits. A parenchymal perianeurysmal cyst is a rare entity; it is crucial to be considered a differential diagnosis in any cystic lesion with the mural nodule.