Pineal Tumor, Pineocytoma

10-year-old male with chronic headaches. The pineal gland is enlarged with a circumscribed T1-hypointense appearance. The lesion is predominately solid, and is both T2- and FLAIR-hyperintense. There is effacement and obstruction of CSF flow at the cerebral aqueduct with mild supratentorial hydrocephalus. The lesion is hypercellular and enhancing. The differential includes, pineocytoma, or pineal parenchymal tumor, pineoblastoma, and germ cell tumors. This is a case of a pineocytoma, which is composed of, uniform, mature cells resembling pineocytes. The lesion is usually well circumscribed, rarely invading surrounding structures. Lesions are usually slow growing, and tend to be less than 3 cm in greatest dimension. If calcifications are present, they tend to have an exploded appearance.