Optic nerve invasion treated with multidisciplinary therapy including proton irradiation in a patient with unilateral retinoblastoma

Abstract

A two-year-old girl was diagnosed as having right retinoblastoma (international classification E) after her mother noticed right eye leukocoria for one month. Contrast-enhanced magnetic resonance imaging (MRI) demonstrated a left–right difference in the optic nerve diameter without any orbital or brain parenchymal lesion. The right eye was enucleated and the cut end of the optic nerve was positive for tumor cells on histopathology. Bone marrow and cerebrospinal fluid analyses showed no tumor invasion. Five courses of chemotherapy were administered, including intrathecal anticancer agents, proton therapy at 45 Gy (RBE)/25 Fr. to the right optic nerve, and high-dose chemotherapy with autologous peripheral blood stem cell transplantation. Five months after treatment completion, there was no recurrence. We expect that the intensified treatment involving both local and systemic approaches is curative despite a tumor-cell-positive surgical margin of the optic nerve. All possible interventions, such as the choice of proton beams and long-term follow-up, could also reduce late complications.