BENIGN GLIAL CYSTS OF THE PINEAL-GLAND - UNUSUAL IMAGING CHARACTERISTICS WITH HISTOLOGIC CORRELATION

PURPOSE: To describe the spectrum of MR and CT findings in clinically symptomatic pineal cysts and to determine whether there are certain di agnostic imaging features that allow one to distinguish a benign pinea l cyst from other neoplasms of the pineal region. METHODS: MR and CT s cans of 19 patients with clinically symptomatic pineal cysts were retr ospectively reviewed. Age range was 15 to 46 years with a mean age of 28 years. There were five male and 14 female patients. RESULTS: Presen ting features included headache (15 patients), diplopia (four), nausea and vomiting (four), papilledema (four), seizure (three), Parinaud sy ndrome (two), ataxia (one), and hemiparesis (one). All cysts were rese cted or biopsied to provide histopathologic confirmation of the diagno sis. Preoperative diagnoses included pineal neoplasm (14 of 19), pinea l cyst (3 of 19), and dermoid cyst (2 of 19). The lesions ranged from 0.8 to 3.0 cm, with a mean diameter of 1.6 cm. Three cysts showed flui d/fluid levels consistent with hemorrhage. Slightly less than half (9 of 19) had evidence of hydrocephalus. The MR signal changes were varia ble but typically demonstrated low signal on Tl-weighted images and hi gh signal on T2-weighted images. More than half (7 of 22) demonstrated enhancement with gadolinium. Calcification of the cyst wall was obser ved in only four of nine patients who had CT studies but identified hi stologically in all cases. CONCLUSION: The MR appearance of benign pin eal cysts is variable, ranging from that of an uncomplicated cystic ma ss to a mass associated with hemorrhage, enhancement, or hydrocephalus . This variability may make them indistinguishable from other pineal-r egion tumors.