Collision of a syncytial meningioma and malignant astrocytoma

The coexistence of two or more primary brain tumors is a relatively rare occurrence. We report an 87-year-old woman with a 5-cm cystic-solid, peripherally enhancing, right frontal lobe mass. The woman presented with progressive hemiparesis, difficulty ambulating, and urinary incontinence. Histologic examination of the surgically excised lesion showed geographically distinct areas of syncytial meningioma (World Health Organization grade I) and malignant astrocytoma (World Health Organization grade III). Focally, infiltration of the meningioma by astrocytoma was observed. Differential diagnostic issues are considered and the literature reviewed.