Contrast-enhanced sagittal T1-weighted magnetic resonance image of the brain demonstrates a large midline cerebral lesion (asterisk) involving the pineal region in a child with bilateral retinoblastoma; this is consistent with a pinealoblastoma (primitive neuroectodermal tumor [PNET]). The presence of the bilateral retinoblastomas and the pineal tumor is referred to as trilateral retinoblastoma.