LGG-56. INFANTILE HEMISPHERIC BRAIN TUMOR WITH A GOPC-ROS1 FUSION GENE: A CASE REPORT

INTRODUCTION: Infantile hemispheric gliomas with ROS1 fusion genes have been reported to have a relatively poor prognosis. Treatment using a ROS1 inhibitor is expected to generate less toxicity and effective for brain tumors with ROS1 fusion genes. CASE PRESENTATION: A one-month-old female presented with a seizure, and a large hypervascular mass in the right hemisphere was found on MRI. The tumor was not biopsied over concerns of an increased risk for bleeding. The mass was clinically diagnosed as an atypical teratoid rhabdoid tumor. She received neoadjuvant chemotherapy using the modified EU-RHAB protocol. The tumor gradually decreased to 70% of its original size with a reduction of vascularity. A near-total resection (> 95%) was performed at eight months of age. Pathological examination revealed the unusual histology with immunostaining positive for INI-1, GFAP, synaptophysin, neurofilament, and slightly positive for NeuN. MIB-1 labeling index was 6%. The pathological diagnosis was a glioneuronal tumor with desmoplastic infantile ganglioglioma-like features, suggestive of low grade. She received adjuvant chemotherapy with carboplatin and vincristine, which is the standard treatment for low-grade gliomas, and achieved a partial response. The GOPC-ROS1 fusion gene was detected in the tumor by FoundationOne(Ⓡ) CDx. CONCLUSION: Chemotherapy may effectively reduce the size of an infant’s brain tumor which is initially considered to be inoperable. A gene profile should be performed as soon as possible in order to direct appropriate management.