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A false aneurysm coexisting with arteriovenous malformation in the cerebellum.

A false aneurysm that developed at the nidus of the cerebellar AVM in a 5-year-old boy is reported. A review of previous reports indicated that non-traumatic false aneurysms occur exclusively in the intraparenchymal brain tissue in association with vascular anomalies. Because the development of a false aneurysm at the nidus of AVM is extremely rare, its possible pathogenesis is discussed.