Pineal cysts-A benign association with familial retinoblastoma.

Patients with familial/heritable retinoblastoma (RB) are at increased risk of developing second malignancies throughout life, including a pineoblastoma (trilateral RB [TRB]) in early childhood. Current guidelines recommend regular surveillance brain imaging for those with heritable RB until 5 years of age. The presence of pineal cysts has been reported in patients with RB. Pineal cysts are thought to arise due to focal degeneration of the pineal gland and can be found incidentally. The finding of pineal abnormalities including cysts in children with RB on imaging is disconcerting, as it raises the possibility of an underlying malignancy, specifically a pinealoblastoma. The authors reviewed the imaging findings and clinical significance of pineal cysts in 69 patients diagnosed with RB at our center between December 1999 and November 2015. Twenty-six patients had pineal cysts found on brain magnetic resonance imaging (MRI) scans performed either at diagnosis or follow-up. Thirty-eight of 69 patients had underlying heritable RB. Nineteen of 38 familial RB patients had a pineal cyst compared with 3 out of 26 with sporadic RB (P = .004). In the majority, the imaging characteristics and size of the cysts remained stable or resolved. In this cohort, pineal cysts were detected at significantly increased frequency in heritable RB. This may be a benign association or may reflect abnormal underlying biology of pineal tissue in individuals highly susceptible to malignancy. Imaging characteristics can be helpful in distinguishing between benign and malignant lesions. The presence of a pineal cyst in patients with unilateral disease may be a useful indicator of underlying heritable RB.