Clinicopathological, Radiological, and Genetic Analyses of Cerebellar Gangliogliomas with Long-Term Survival.

Abstract

Cerebellar gangliogliomas show different image findings and clinical behaviors from the supratentorial; however, their molecular basis and optimal managements remain to be elucidated. We report 3 children with cerebellar ganglioglioma and long-term survival, focusing on clinicopathological and radiological findings and genetic analyses. We retrospectively analyzed 3 children with cerebellar ganglioglioma treated in our institute between 2000 and 2010. Immunohistochemical examinations were performed to determine the expression of KI-67, glial fibrillary acidic protein, synaptophysin, BRAF^V600E and IDH-1 R132H mutated proteins. Standard Sanger sequencing was used to confirm BRAF, IDH-1/2, and Histone H3.3 mutations. Methylation-specific polymerase chain reaction was used to evaluate MGMT promoter methylation. In all cases, magnetic resonance imaging demonstrated an infiltrative tumor in cerebellar peduncle and hemisphere. All 3 children are alive (>12 years survival), and their residual tumors have been stable for more than 5 years after the treatments. Their tumors showed distinctive features of ganglioglioma with low Ki-67 index (2%-4%), positive for the BRAF^V600E mutation, but negative for IDH1/2 mutations. The MGMT promoter methylation was observed in all of them. Our study showed that all 3 children achieved long-term survival with residual tumors. These tumors might indicate a benign prognosis of pediatric cerebellar gangliogliomas, regardless of the infiltrating manifestation and the presence of BRAF mutation.