Diffuse Intrinsic Pontine Gliomas (DIPG) appear almost exclusively in children and adolescents, representing 15 to 20% of posterior fossa tumours. Even if it is one of the most common malignant brain tumours, there are only 30 to 40 new cases per year in France. Their clinical presentation is stereotyped with a short clinical history and a unique MRI appearance that was usually considered as sufficient to establish the diagnosis. The prognosis of DIPG is always unfavourable; median overall survival is 9 to 10 months in general and most patients will die within two years after diagnosis (Kaplan 1996,Hargrave 2006). Malignant gliomas infiltrating the brainstem represent the greatest challenge of paediatric oncology; despite numerous collaborative studies performed, patients' survival has not significantly increased in thirty years (Hargrave 2009). There is no validated prognostic factor. There is currently no validated treatment except radiotherapy.