Intracerebral hemorrhage caused by a neoplastic aneurysm from pleomorphic lung carcinoma.

A 61-year-old man presented with an extremely rare neoplastic cerebral aneurysm caused by brain metastasis from pleomorphic lung carcinoma manifesting as intracerebral hematoma and sudden onset of semicoma. Computed tomography demonstrated huge intracerebral hemorrhage in the left cerebral hemisphere, which had collapsed into the lateral ventricle. Cerebral angiography disclosed a fusiform aneurysm in the periphery of the left middle cerebral artery (approximately 2 mm diameter). Resection of the aneurysm and removal of the hematoma were performed. Histological examination revealed that the aneurysm walls were invaded by pleomorphic carcinoma. The present case indicates that neoplastic cerebral aneurysm may be the cause of intracerebral hemorrhage in patients with pleomorphic lung carcinoma.