Ruptured and unruptured blebs shared a distinctive pattern of low WSS and high OSI. The degree of WSS at the rupture site was significantly lower than in the unruptured thin-walled blebs.
Pilocytic astrocytoma sometimes transforms to a malignant type, and previous radiation therapy is considered to be a key factor. We report a case of pilocytic astrocytoma with histological malignant features without previous radiation therapy. A 21-year-old man presented a sudden onset of severe headache. Neuroimaging had detected a cystic mass in the posterior fossa at the age of one year without therapeutic intervention. On admission, computed tomography depicted a brain tumor in the posterior fossa with cystic components, intratumoral hemorrhage, and upward herniation. Urgent surgery was performed, and histological examination revealed some features of pilocytic astrocytoma but also broad necrosis, high cellularity, and MIB-1 labeling index of more than 20%. The histological diagnosis was pilocytic astrocytoma with malignant features. This tumor had continued a benign clinical course for 20 years, but had eventually transformed to a malignant type. Therefore, pilocytic astrocytoma may undergo spontaneous malignant transformation during its natural clinical course.
BackgroundWhile hemodynamic stress can result in aneurysm formation, it rarely contributes to the development of peripheral aneurysms in collateral pathways. We report two patients with ruptured distal aneurysms in a collateral pathway associated with stenosis of a major cerebral artery.Case DescriptionA 67-year-old man presented with intracerebral hemorrhage in the right frontal lobe. Digital subtraction angiography (DSA) revealed severe stenosis of the right middle cerebral artery and two aneurysms in the collateral pathway of the right anterior cerebral artery. The ruptured aneurysm was trapped and resected; histologically, it was a true saccular aneurysm. The unruptured aneurysm was clipped and the patient was discharged without additional neurological deficits. The second patient was a 73-year-old woman with subarachnoid hemorrhage. DSA revealed three arterial dilations. On the 7th day of hospitalization, one of the aneurysms in a posterior inferior cerebellar artery–anterior inferior cerebellar artery anastomosis that functioned as a collateral pathway in the presence of severe basilar artery stenosis was found to be enlarged. It was treated by selective aneurysmal coil embolization with parent artery preservation. Her postoperative course was uneventful and she was discharged without any neurological deficits.ConclusionWe document the successful treatment of two patients with ruptured aneurysms in the peripheral portion of a collateral pathway. We discuss the histology of peripheral aneurysms and present a review of the literature.
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