Relying too much on upfront radiosurgery: Indolent course misinterpreted as effectiveness of radiosurgery in a case of skull base chondrosarcoma

Abstract

Background: Skull base lesions are still considered surgically challenging and primary gamma knife radio surgery (GKRS) is gaining popularity. However the effectiveness of GKRS may be overrated especially in lesions with indolent course.

Case description: We report a case of chondrosarcoma, mimicking a trigeminal schwannoma treated with upfront radio surgery. Relatively lower dose was administered in view of proximity to the brainstem. The patient was asymptomatic and the size of the lesion remained static for over a decade. This was misinterpreted as effectiveness of GKRS. The lesion grew after a decade necessitating surgery.

Conclusion: With popularity of upfront GKRS, suboptimal but maximal safe radiation dose is usually prescribed for lesions close to critical structures like brainstem. In these cases the long indolent natural course of the pathology, as in the case of chondrosarcoma may be misconstrued as success of radiosurgery. An extended follow up beyond this static period is necessary before concluding its effectiveness.

Keywords: Chondrosarcoma; Gamma knife radiosurgery; Indolent course; Skull base.