Trilateral retinoblastoma is usually associated with a pineal or, less commonly, a suprasellar lesion. In patients with the hereditary form of retinoblastoma, CNS disease is less likely the result of metastatic or regional spread than a primary intracranial focus, such as a pineal tumor. The prognosis for patients with trilateral retinoblastoma is very poor; most patients die of disseminated neuraxis disease in less than 9 months. While pineoblastomas occurring in older patients are sensitive to radiation therapy, current strategies are directed towards avoiding irradiation by using intensive chemotherapy followed by consolidation with myeloablative chemotherapy and autologous hematopoietic progenitor cell rescue, an approach similar to those being used in the treatment of brain tumors in infants.
Because of the poor prognosis of trilateral retinoblastoma, screening neuroimaging is a common practice. While it is not clear whether early diagnosis can impact survival, the frequency of screening with magnetic resonance imaging for those suspected of having hereditary disease or those with unilateral disease and a positive family history has been recommended as often as every 6 months for up to 5 years. Given the short interval between the diagnosis of retinoblastoma and the occurrence of trilateral retinoblastoma, routine screening might detect the majority of cases within 2 years. However, it is not clear that screening by neuroimaging improves survival. Computed tomography scans should be avoided for routine screening in these children because of the perceived risk of exposure to ionizing radiation.
Extracranial metastatic retinoblastoma
Hematogenous metastases may develop in the bones, bone marrow, and less frequently, in the liver. Although long-term survivors have been reported with conventional chemotherapy, these reports should be considered anecdotal; metastatic retinoblastoma is not curable with conventional chemotherapy. In recent years, however, studies of small series of patients have shown that metastatic retinoblastoma can be cured using high-dose marrow-ablative chemotherapy and autologous hematopoietic stem cell rescue.[5,6,7,8,9,10]; [Level of evidence: 3iiA]
There is no clearly proven effective or standard therapy for the treatment of extraocular retinoblastoma, although orbital irradiation and chemotherapy have been used. In the past, palliative therapy with radiation therapy (including craniospinal irradiation when there is meningeal involvement) and/or intrathecal chemotherapy with methotrexate, cytarabine, and hydrocortisone, plus supportive care has been used. A retrospective study showed that extraocular disease, manifested by gadolinium enhancement on magnetic resonance imaging of the proximal optic nerve, might respond to treatment with neoadjuvant chemotherapy prior to enucleation.[Level of evidence: 3iiDi]