Dorsally exophytic glioblastoma of the pons.

Brainstem gliomas are rare tumours in adults, accounting for only 1%-2% of all intracranial gliomas. They are recognised as a heterogeneous group, in which most are malignant tumours. Brainstem gliomas are classified into four major groups according to the growth pattern on imaging, namely diffuse, focal, exophytic and cervicomedullary.