Parenchymal perianeurysmal cystic changes in the brain: Report of five cases

PURPOSE: To describe parenchymal perianeurysmal cystic changes in the brain . MATERIALS AND METHODS: Among 247 patients with cerebral aneurysms described in the medical or radiologic records in three institutions, five had peria neurysmal cystic changes. These were evaluated with computed tomography or magnetic resonance (MR) imaging and were categorized according to size, app earance, and the presence of hemosiderin deposit. Confirmation at stereotac tic needle biopsy was available in one case. RESULTS: Perianeurysmal cysts comprised multiple clustered cysts in three c ases and a unilocular cyst in two, and diameters were 1.5-3.5 cm. Hemosider in was depicted at MR imaging in one unilocular cyst. Associated aneurysms had diameters of 0.7-4.0 cm, and prominent aneurysmal thrombosis and calcif ications were seen in two cases. Findings at stereotactic needle biopsy wer e of mild reactive gliosis, At long-term follow-up in two patients, the cys tic regions were stable. CONCLUSION: Parenchymal perianeurysmal cysts are rare and may display vario us morphologic characteristics from unilocular to multilocular. Since there may or may not be evidence of previous hemorrhage, other mechanisms such a s abnormal angiogenesis factors may play a role.