A Case of Multiple Intracranial Hemorrhages due to a Ruptured Neoplastic Cerebral Aneurysm Secondary to Metastasis of Poorly Differentiated Parotid Gland Carcinoma.

Neoplastic cerebral aneurysms (NCAs) are rare. This study reported a case of an NCA secondary to a poorly differentiated carcinoma of the parotid gland. An 84-year-old Japanese woman undergoing treatment for parotid gland cancer was admitted to our hospital with headache and progressive loss of consciousness. Based on computed tomography (CT) and CT angiography (CTA), a diagnosis of subarachnoid hemorrhage due to rupture of a left posterior inferior cerebellar artery aneurysm was made, and emergency aneurysmectomy was performed. Pathological examination of the resected aneurysm showed an NCA secondary to parotid carcinoma. After the aneurysmectomy, her condition stabilized; however, 33 days later, the patient developed an intracerebral hemorrhage, and a new aneurysm was confirmed in the right middle cerebral artery. To the best of our knowledge, there have been no previous reports on cases of NCAs secondary to parotid carcinoma. The pathology and clinical course strongly suggest that NCAs derived from malignant tumors may have an aggressive course.