ABSTRACT
Cyst-associated tumors are classified as cysts with neoplastic mural nodules and intratumoral cysts. The solid component of many of these tumors may be appropriate for gamma knife radiosurgery (GKS). At present there is no systematic protocol for GKS treatment of patients harboring tumors with a cystic component. The purpose of this paper is to suggest such a program. Two cases are presented. One patient had a hemangioblastoma with a cyst and a mural nodule. The second patient had a craniopharyngioma with one large and two small intratumoral cysts. The course in both cases has been satisfactory in the short term. Although the 1-year follow-up period, however, does not provide a basis for determining the correct overall management of such tumors, the treatment strategy does illustrate a program for the management of tumors with associated cysts. Cysts with tumor nodules in their walls should first be treated with GKS followed by aspiration of the cyst contents, unless special circumstances make this unsuitable. This strategy enables treatment planning to take advantage of the natural barrier a cyst may place between a tumor and important surrounding structures. Intratumoral cysts may be aspirated and then treated with GKS, with every attempt made to cover the entire target volume including any residual cyst with the prescription dose. This form of treatment requires very careful follow up. It is probable that in some cases reaccumulation of cyst fluid may require the insertion of an Ommaya reservoir for repeated aspiration or the installation of cytotoxic agents such as bleomycin. This form of treatment is much less traumatic than surgery and does not hinder the performance of subsequent surgery, should this become necessary.
