An Extremely Rare Case of Collision Tumor: A Craniopharyngioma Coexists Pilocytic Astrocytoma.

A 21-year-old man presented with a 2-day history of cephalalgia and a 1-day history of nausea and vomiting. Neuroradiologic imaging revealed a lesion in the third ventricle accompanied by hydrocephalus. After undergoing a ventriculoperitoneal shunt procedure, the patient experienced relief from symptoms. One-month post-shunt, we excised the tumor. Histopathological examination identified it as a rare collision tumor, composed of a mixture of craniopharyngioma and pilocytic astrocytoma. This is an exceedingly rare type of tumor, with no similar cases reported in the existing literature.