[Pineocytoma associated with a cyst: report of a case].

We report a case of pineocytoma associated with an unusually large cyst. A 15-year-old boy was admitted with a complaint of intermittent headache. Neurological examination was normal except for bilateral papilledema. CT scan showed triventricular hydrocephalus and a large mass. A solid portion of the tumor in the pineal and retrothalamic areas was isodense, and contained massive calcification on CT. A huge cystic portion extended far into the infratentorial, supracellebellar area. On MR, the solid tumor showed isointensity on T1-WI and iso- to high intensity on T2-WI, and was enhanced by Gd-DTPA. After a ventriculo-peritoneal shunt, the tumor was partially removed through an occipital supratentorial approach. Histological examination revealed a pineocytoma with neuronal and astrocytic differentiations. Reviewing the literature, it is most unusual to find a pineocytoma associated with a huge cyst as was seen in this case.