[Pineal cyst: its diagnosis and treatment].
ABSTRACT Four cases of pineal cyst were presented and their features on magnetic resonance (MR) imaging were discussed while reviewing the literature relevant to this clinical entity. Pineal cyst is a normal developmental variant and in most of the cases its diagnosis is not difficult, but in a limited number of cases, pineal cyst needs to be differentiated from cystic tumors which have developed in the region of the pineal gland, such as pineocytoma or astrocytoma. Most pineal cysts are found incidentally during MR screening studies and no surgical interventions are needed. Pineal cysts should be considered for surgery only when the diameter of the cyst is more than 1.0cm, or when obstructive hydrocephalus is verified on MRI or CT, and/or when definitive neurological signs such as Parinaud's syndrome are present. It was also stressed that embryological considerations are indispensable for evaluating pineal cysts on MR images.