A rare case of posterior fossa collision tumor involving low-grade astrocytoma and meningioma

This case highlights a rare phenomenon, of two benign tumors, a low-grade astrocytoma, and meningioma, occurring simultaneously in the infratentorial compartment. This unique case seeks to add to the current literature on collision tumors. A 25-year-old female presented with a 9-month history of neck pain and right arm weakness. Imaging demonstrated a ring-enhancing cystic lesion in the posterior fossa, with solid enhancing extension into the spinal canal. The main differential diagnosis was an ependymoma. A suboccipital craniotomy, C1 laminectomy and C2–C4 laminoplasty, was performed and revealed two distinct tumor entities. Histopathology revealed that the cerebellar component was consistent with a low-grade astrocytoma and the extra-axial component was a meningioma. Coexisting tumors of different cell lineage and distinct borders, collision tumor, are very uncommon in clinical practice, with most cases diagnosed intra and post-operatively. A complete medical and genetic assessment is critical for the holistic management of these patients.