Background: Patients with hereditary Retinoblastoma (RB) are at risk of developing other types of extraocular primary malignancies throughout life. Among these tumors, pinealoblastoma is a type of malignancy that appears in the pineal gland and can develop at any time from the diagnosis of bilateral retinoblastoma.Objective: To present an unusual case of a patient with a diagnosis of hereditary BR who developed a pineal cystStudy design: Case report.Case summary: We present in this article the case of a patient with a diagnosis of hereditary BR with remission who developed a pineal cyst during clinical follow-up. The cystic lesions of the pineal gland reported by magnetic resonance are infrequent in pediatric age, however its incidence is increased in patients with RB, which generates uncertainty about the possibility of the development of a primary pineal gland malignancy. The pathophysiological mechanism of pineal gland cysts in patients with hereditary RB is still unknown, but it could be related to a genetic alteration or to chemotherapy treatment that these patients receive for the primary intraocular tumor.Conclusion: The imaging characteristics are fundamental to differentiate between benign and malignant lesions of the pineal gland in patients with Hereditary Retinoblastoma and to make a close follow up.