A cystic cerebral hemispheric glioma presenting as an exophytic growth into the Sylvian cistern

•Exophytic growth pattern of PXA-GGs arising from cerebral hemisphere is rare.•A case of PXA-GG growing exophytically into the Sylvian fissure is presented.•Pressure gradient among surrounding tissue might cause exophytic growth of PXA-GGs. An exophytic growth pattern is relatively common in brain stem gliomas, whereas the pattern is rarely seen in cerebral hemispheric gliomas, probably due to fewer neuronal fibers in the cerebral hemisphere than in the brain stem. A rare case of a cystic glioma in a cerebral hemisphere with an exophytic growth pattern is presented. A 64-year-old woman was admitted to our hospital due to sensory aphasia and a mild gait disturbance. Contrast T1-weighted magnetic resonance imaging (MRI) demonstrated a cystic lesion with a small enhancing nodule adjacent to the left Sylvian cistern. Since congestive heart failure was detected on preoperative examination, and there was concern about the risk of perioperative cardiac complications, an Ommaya reservoir was implanted for rapid control of intracranial pressure under local anesthesia, resulting in rapid recovery from the primary symptoms. T2-weighted MRI obtained after cyst aspiration showed an exophytic nodule localized at the medial temporal cortex. Until the heart failure was stabilized, cyst aspiration was continued once every three weeks postdischarge at the outpatient clinic. A year after first admission, she underwent subtotal removal of the tumor under general anesthesia. Histopathological examination showed large cells with pleomorphic nuclei and ganglion cells with fascicular growth of spindled cells side by side, suggesting a diagnosis of composite pleomorphic xanthoastrocytoma-ganglioglioma. The patient has been free from primary symptoms and tumor recurrence for 1 year. A rare case of a cystic glioma with an exophytic growth pattern was reported. The combination of histopathological characteristics and a pressure gap between the cyst and the Sylvian cistern might be related to the exophytic growth pattern of the tumor.