Giant aneurysms of the posterior fossa suspected as neoplasms on computed tomography.

Giant intracranial aneurysms of the vertebral and basilar artery can be mistakenly diagnosed as neoplasms of the posterior fossa on the basis of their clinical presentation and CT findings. The following report of three cases of tumorous aneurysms emphasizes the complementary value of angiography and computed tomography for the localization and correct diagnosis of space-occupying lesions of the posterior fossa.