Object. The authors assessed the long-term result of gamma knife surgery (GKS) for hemangioblastomas of the brain (HABs) and show histopathological findings after GKS.
Methods. Thirty-five patients, 28 men and seven women, with a mean age of 36 years underwent GKS. Eighteen patients presented with multiple tumors and 17 with a solitary tumor. Twenty-one patients had von Hippel—Lindau (VHL) disease. The mean tumor diameter was 13 mm (range 5–55 mm). The mean follow up after GKS was 66 months (range 24–114 months). The mean prescription dose was 17.2 Gy (range 12–24 Gy) at the tumor margin. For tumors close to or within the brainstem a prescription dose of 12 to 13 Gy was used.
At the most recent follow up, 29 patients were alive, six were dead, and satisfactory tumor control had been achieved in 29. A stable or improved neurological status was obtained in 21 patients. Eight patients underwent open surgery because of tumor-associated cyst enlargement or the development of new tumors after GKS. Seven patients developed new tumors and five of them required a second GKS. The 1-year tumor control rate was 94%; 2 years, 85%; 3 years, 82%; 4 years, 79%; and 5 years, 71%. Histopathology showed that no tumor cells were found and there was degeneration and necrosis in a tumor nodule 48 months after GKS with a prescription dose of 18 Gy.
Conclusions. Gamma knife surgery was a useful choice for small- or medium-sized, solid HAB in the long term, especially when the tumor margin dose was 18 Gy. Although GKS can treat multiple tumors in a single session, for HABs associated with VHL disease, GKS faces the dual problems of tumor recurrence or development of a new tumor.