As previously noted, one of the top prospects in the Boston Red Sox organization, Ryan Westmoreland, has been diagnosed with a cavernous hemangioma. He is going to undergo surgery. I thought this might be an opportune time to discuss the nature, management, and prognosis of cavernous hemangiomas.
Cavernous hemangiomas, also known as cavernous malformations or
cavernomas, are uncommon vascular anomalies. It is uncertain whether they occur de novo or can develop throughout life. They consist of a bundle of large, thin-walled blood vessels without any intervening brain.
They cause problems because they can bleed into the brain. 
Unlike the arteriovenous malformation (AVM), cavernous malformations are a relatively low-pressure system. That means that they generally not capable of the high-pressure, extensive hemorrhages that characterize AVMs and aneurysms. They can, however, cause problems. Usually, when a cavernoma is found, it has a characteristic appearance on an MR scan commonly called a popcorn lesion. The popcorn effect is due to the multiple small hemorhages surrounding the cavernoma. A cavernoma is most readily apparent on a gradient echo series because of the local hemosiderin staining.
The majority of cavernomas are supratentorial (80%), but they can also occur in the cerebellum, brainstem, and spinal cord. Symptoms are derived from dysfunction of affected adjacent structures. Supratentorial lesions rarely induce symptomatic hemorrhages. More frequently, supratentorial cavernous hemangiomas induce seizures.
Hemorrhages from cavernomas of the brainstem and spinal cord frequently cause more symptoms. In the brainstem and spinal cord, smaller hemorrhages are more likely to damage vital territory such as motor and sensory function.
The risk of symptomatic hemorrhage from a cavernous malformation is approximately 1% per year.
Surgery for cavernomas is not emergent. Frequently, however, it is most convenient to pursue surgery shortly after a hemorrhage. The hemorrhage can help in localization of the cavernoma. It can also partially dissect the cavernoma free facilitating it’s removal. This also permits the patient to recover from both surgery and the hemorrhage simultaneously instead of sequentially.
Most cavernomas are sporadic, although there is a familial form that is most common in hispanics.
