Introduction: Carcinomas of the choroid plexus are a rare malignant variety of papillary tumours which originate in the choroid plexus. Their occurrence in adults has been questioned because of the difficulty in differentiating them from the metastases of adenocarcinomas.
Clinical case and conclusions: We present the case of a 57 year old man with a rapidly progressive illness characterized by disorientation, behaviour changes and amnesia, progressive deterioration of the level of consciousness until he was in deep coma and died (all within one month). There was no clinical evidence of the presence of a primary extra-cranial tumour. On magnetic resonance there was obliteration of the ventricular system with a protein material and thickening and increased marking of the ependyma walls, compatible with ventriculitis. Necropsy, limited to the skull, showed the presence of a malignant infiltrating tumour with papillary morphology, which affected the choroid plexuses of the whole ventricular system, infiltrated the adjacent nervous tissue and extended to the leptomeninges. These findings suggest a differential diagnosis between carcinoma of the choroid plexus and metastatic meningeal carcinoma.