A diffuse intrinsic pontine glioma (DIPG) is a tumor located in the pons (middle) of the brain stem. The brain stem is the bottommost portion of the brain, connecting the cerebrum with the spinal cord. The majority of brain stem tumors occur in the pons and are diffusely infiltrating (they grow amidst the nerves), and therefore cannot be surgically removed. Glioma is a general name for any tumor that arises from the supportive tissue called glia, which help keep the neurons in place and functioning well. The brain stem contains all of the afferent (incoming) neurons within the spinal cord, as well as important structures involved in eye movements and in face and throat muscle control and sensation.