Treatment strategy and pathological background of radiosurgery for craniopharyngiomas.

In this paper, pathological aspects of diagnosis, classification, treatment strategy and interstitial radiotherapy for craniopharyngiomas have been discussed and reviewed. The classification based on the location of squamous cell nests is useful for clinical evaluations and/or surgical approaches. Two pathological patterns, adamantinomatous and squamous cell types, are well correlated to the age of the patient, nature and response of tumor to radiation therapy. The originating portion of tumor (so called 'R site') at the retrochiasmal and anterior part of the stalk showed close contact of tumor with hypothalamic neurons without arachnoid membrane or glial cleavage. This means that the total removal of the tumor is difficult without damage to the stalk and optic pathway. A new concept of strategy can be proposed that a small tumor at this portion is intentionally left behind and is treated by gamma radiosurgery. The treatment strategy for large cystic tumor has been important and two methods can be recommended. The use of an Ommaya draining system has been useful not only for internal irradiation but also for collapse of the cyst prior to gamma radiosurgery. The effectiveness of interstitial radiation therapy has been evaluated by the surgical specimen using various immunohistochemical studies.