There is no standard staging system for childhood brain stem glioma. Instead, the plan for cancer treatment depends on whether the tumor is diffuse (spread throughout the brain) or focal (in one area of the brain):
Diffuse intrinsic pontine glioma is a tumor that has spread widely throughout the brain stem. A biopsy is usually not done for this type of brain stem glioma and it is not removed by surgery. A diffuse intrinsic pontine glioma is usually diagnosed using imaging studies.
Focal or low-grade glioma is a tumor that is in one area of the brain stem. A biopsy may be done and the tumor removed during the same surgery.