A 39-year-old female was admitted to the hospital because of a sudden meningeal syndrome followed by diplopia, cervical, dorsal and sciatic nerve pains, and right peripheral facial palsy. Cerebrospinal fluid obtained by lumbar puncture showed a protein level at 23 g/l. Myelography and magnetic resonance imaging (MRI) were in favor of a lumbar arachnoiditis. A meningeal biopsy revealed a tumour infiltration with foci of cells that were stained with anti-glial fibrillary acidic protein antibody. Cerebral MRI was performed to search for a central nervous system (CNS) primary tumour, and disclosed a pineal mass. Five months after the onset of the disease, the patient worsened her clinical state and died. Necropsy confirmed the presence of a pineocytoma with astrocytic differentiation and diffuse leptomeningeal spread. This exceptional occurrence leads us to discuss about primary tumours of the CNS with leptomeningeal spread.