Natural course of pineal cysts-a radiographic study.

We found that PCs are a dynamic structure that may change in size during the patient's lifetime. Patients with an increase in PC size were significantly younger than patients with a decrease in size. Therefore, PC growth in the first, second, and third decennium is normal and does not justify medical intervention. Surgery is indicated in cases of hydrocephalus and Parinaud's syndrome or in atypical cysts when neoplasia is suspected. The size of a PC does not predict PC behavior in terms of a future increase or decrease in size.