Upfront Gamma Knife Surgery for Giant Central Neurocytoma.

Background: In this report, we present the results of using upfront Gamma Knife surgery (GKS) in the management of giant central neurocytoma (CNC) (volume >50 mL) without the initial removal of the tumor mass.

Case Descriptions: Two patients underwent GKS for histologically proven CNC. Clinical and imaging studies were performed to evaluate the response to treatment. GKS involved delivery doses of 12 or 13 Gy to the tumor margin at the isodose line of 50%. Tumor response to GKS appeared as early as 4-6 months after GKS, at which point a dramatic reduction in volume was observed. No adverse effects of radiation or new neurologic deficits were observed in either of the cases. In case 1, we observed a reduction in tumor volume from 69 to 20 mL at 6 months and a further reduction to 10.3 mL at 86 months. In case 2, we observed a reduction in tumor volume from 62 to 31 mL at 4 months with a further reduction to 22.5 mL at 30 months. The female patient (case 1) showed mild weakness in the right lower limb after the minimal surgical removal of tumor using the cortical approach. No additional neurologic deficits were observed after GKS. The young male patient (case 2) presented a complete recovery without any signs of headache at 3 months after GKS.

Conclusions: Based on this initial experience, it appears that GKS is an effective treatment for CNC and may be used for upfront management in cases of indolent clinical symptoms, even when the tumor is very large.