Utility of intraoperative fluorescent diagnosis of residual hemangioblastoma using 5-aminolevulinic acid

Hemangioblastoma is a benign tumor of the cerebellum, and treatment involves surgical excision, both as the initial treatment and also in case of recurrence. Recurrence of hemangioblastoma can be local due to incomplete resection or can be distant and separate from the tumor resection region. Local recurrence can largely be avoided by verifying for any residual tumor intraoperatively before closure. In this study, we used intraoperative fluorescent diagnosis using 5-aminolevulinic acid (5-ALA) to verify the presence of a residual tumor during surgical resection. Nine patients with hemangioblastoma were given 1 g of 5-ALA orally before surgery, and a laser beam of 405 nm was focused on the tumor during resective surgery. Fluorescence of protoporphyrin IX (PPIX) was observed in the core of tumor in all the cases. Fluorescence of PPIX was observed in the peritumoral cyst wall in two patients after tumor resection, and in both of them fluorescent parts of PPIX were resected and histological examination showed tumor cells. Usually, there are no tumor cells in the peritumoral cyst of a hemangioblastoma, yet hemangioblastomas may sometimes recur from an unresected cyst wall. It is thus necessary to excise an infiltrating cyst of tumor cells to prevent recurrence. Intraoperative fluorescent diagnosis using 5-ALA is a useful method to discern whether tumor cells are present in the peritumoral cyst wall of a hemangioblastoma.

Keywords
5-aminolevulinic acid, cyst wall, fluorescence diagnosis, hemangioblastoma, residual tumor