Intracranial perianeurysmal cyst: still a dilemma. A case report with endovascular management.

Intracranial perianeurysmal cysts constitute an extremely rare entity with very few cases reported in the literature. These cysts present an unknown mechanism of formation and clinical significance. Several theories based on isolated cases have been proposed, without drawing a clear conclusion. It is also unknown if follow-up with imaging techniques is required or which is the most appropriate treatment. We describe an atypical case handled with a satisfactory outcome after endovascular treatment, suggesting the importance of hydrodynamic forces as the key factors in the mechanism of formation. We believe that this case can help in future analysis of this rare entity.