Risk of hemorrhage in hemangioblastomas of the central nervous system.

OBJECTIVE: Hemangioblastomas are benign vascular tumors of the central nervous system. Several cases of spontaneous hemorrhage within these tumors have been reported. However, the risk of hemorrhage in these tumors remains unknown.
METHODS: To clarify the incidence of hemorrhage in hemangioblastomas, we reviewed our large clinical database of 277 patients with central nervous system hemangioblastomas for the incidence of spontaneous or perioperative hemorrhage. Clinical characteristics such as tumor size, tumor location, von Hippel-Lindau disease status, and clinical symptoms before hemorrhage were correlated with hemorrhage risk. Furthermore, we reviewed the literature for cases of spontaneous hemorrhage from hemangioblastoma.
RESULTS: Among all patients in our series, we observed seven cases of spontaneous hemorrhage from a hemangioblastoma within the summarized follow-up time. Thus, we calculate a spontaneous hemorrhage probability of 0.0024 per person per year. The average diameter of tumors that bled was 3 cm in our series and 2.3 cm in the literature review, whereas the average diameter of hemangioblastomas in major series ranges from 0.8 to 1.1 cm. Furthermore, we have observed severe postoperative hemorrhage in two extraordinarily large solid hemangioblastomas (4 and 5 cm).
CONCLUSION: The overall incidence of hemorrhage in patients with hemangioblastoma is low. An important indicator for the probability of hemorrhage is tumor size, as spontaneous or postoperative hemorrhage occurred exclusively in extraordinarily large tumors. Hemangioblastomas smaller than 1.5 cm (the vast majority of these tumors) harbor virtually no risk of spontaneous hemorrhage.