A skull base tumor grows along the bottom part of the skull, mostly on the inside but also on the outside of the skull. Examples of skull base tumors include meningiomas, pituitary adenomas, craniopharyngiomas, acoustic neuromas and chordomas. Treatment of skull base tumors is different from treatment of other tumors because of the surgical approach required. The techniques for removing these tumors have improved dramatically because of new technological advances and perfected microsurgical techniques. Once a skull base tumor has been identified, additional specialized diagnostic tests may be required to evaluate the tumor and the relationship of the tumor to surrounding structures.