Hemangioblastomas of the cerebellum, brainstem and spinal cord are frequent tumors in patients with von Hippel-Lindau (VHL) disease. Rarely, these lesions also affect the cerebrum. Patients often have multiple lesions, many of which are associated with cysts or syrinx. The current treatment for symptomatic lesions is surgical resection. Focused radiation is also being used in selected cases in an attempt to provide tumor control. The natural history of central nervous system (CNS) lesions in patients with VHL has not been addressed in a prospective study. It is not clear at which point these lesions will begin to grow, or develop cysts in the cerebellum or syrinx in the spinal cord, and systemic factors that influence tumor growth have not been identified. By identifying factors that predict or influence tumor progression or cyst development, we can more accurately recommend surgical or medical intervention at appropriate times and avoid unnecessary treatment for stable lesions. This study will collect prospective radiological and clinical data on growth of the central nervous system (CNS) hemangioblastomas and associated cysts. We will also prospectively collect information on systemic processes that may influence tumor progression, such as puberty, menopause, pregnancy, effects of hormone therapy, tumor load, serum VEGF levels, hemoglobin/hematocrit levels, and erythropoietin.