Intracranial aneurysms mimicking third ventricular masses: case series and systematic review.

Objective: Intracranial aneurysms presenting as third ventricular and adjoining part masses are rare and are always associated with obstructive hydrocephalus. It is vital to provide precise diagnostics and apt treatment for such patients since endovascular or microsurgical operations remain challenging. This study aimed to discuss differential diagnosis tactics based on the cases we followed and the current literature on intracranial aneurysms mimicking third ventricular masses. Methods: We followed a case series of intracranial aneurysms presenting as third ventricular masses. Literature reports related to aneurysms adjoining the third ventricle since 1979 were systematically reviewed and summarized. Results: Twenty-seven cases of this disease were collected. A total of 92.6% of cases developed hydrocephalus. Six cases were reported as third ventricular tumors in primary radiologic reports, and misdiagnosis hindered subsequent clinical decisions. We found a significant correlation between thrombosis and misdiagnosis, as well as between misdiagnosis and craniotomy rate. There are also false negative angiography reports for aneurysms from our cases and literature review. Strategies for the diagnosis and treatment of these aneurysms have changed over time. The uniqueness of our cases sheds light on the use of CT angiography, which has proven to be an appropriate test for diagnosis and reexamination but was not widely applied in previous reports. VW-MRI may be useful to assess rupture risk. Distinct treatment strategies show no significant difference in prognosis. Conclusions: Thrombosed aneurysms should be considered as a differential diagnosis in patients with third ventricular masses. Application of CTA and VW-MRI can be beneficial. Aneurysm coil occlusion might be a favorable treatment for cases with mass effects. Further studies should be conducted to confirm our observations.