More than 50% of neoplasms in the brain are metastatic, and about 40% of malignancies are complicated with brain metastasis in their course. Brain metastases often happen in end-stage malignancies within 1–2 months of survival without treatment and 6 months of survival with treatment. The most common brain metastases are from the lungs, kidneys, breasts, and melanomas or colorectal neoplasms [6, 7]. Bleeding into intracranial neoplasms happens in 1.3% to 14.6% of intracranial metastases . Hemorrhagic brain parenchymal metastases are well-known hyper-vascular conditions, occurring in melanomas, renal cell carcinomas, choriocarcinomas, and in cancers of breasts and thyroid gland.
Several mechanisms for bleeding within the cerebral metastases have been proposed, including over-expression of vascular endothelial growth factor, imbalances in the fibrinolytic cascade, rapid tumor growth and vascular invasion, neo-vascularization, and tumor necrosis . Despite the high prevalence of prostate cancers, cerebral parenchymal metastases from prostate cancers are uncommon and usually happen in patients with other osseous and soft tissue metastases. In recent years, the increased incidence of brain parenchymal metastases from prostate cancers might be due to improved survival secondary to effective hormonal, radiation, and immune therapies. The most common presentation in these patients is nonfocal neurologic symptoms related to intracranial hypertension. These include confusion, headache, and memory deficits. However, hemiparesis, seizures, and aphasia are less common. The parenchymal metastases are often located in the supratentorial rather than infratentorial area .
It has been reported that one third of the prostatic metastases to the brain are hemorrhagic and 19% are cystic or necrotic . Micro-hemorrhages are usually seen on SWI and gradient recalled echo (GRE) sequences. Another intracranial presentation of prostate cancer is metastasis to the dura mater. In this context, prostate cancer is the most common malignancy with dural metastases, followed by breast and lung malignancies . Despite the high prevalence of micro-hemorrhages in prostatic parenchymal metastases , subarachnoid and intraventricular hemorrhages are very rare. To our knowledge, only one case of intraventricular hemorrhage has been reported due to prostatic metastasis since the 1980s .
Strength of the study
The current case report is unique in many ways, based on the CT and MR images. These include the initial intraventricular hemorrhage, acute hydrocephalus, and a large exophytic hemorrhagic metastasis from the hypothalamus extended to the suprasellar cistern, with the morphology suggestive of a giant thrombotic aneurysm. In this case, the lesion’s location being adjacent to the hypothalamus, peripheral parenchymal edema, lack of subarachnoid hemorrhage, and lack of visible feeding artery were the helpful information to exclude a possible aneurysm. Lastly, the hypernatremia found in this case was likely due to the patient’s history of diabetes insipidus. To the best of knowledge, this is the first case of exophytic hypothalamic prostatic metastasis that mimicked a ruptured aneurysm.
Limitation of the study
Unfortunately, the patient passed away after the intraventricular shunt placement and biopsy of the hypothalamic lesion. Therefore, no additional imaging, such as digital subtraction angiography (DSA), is available and the extent of the systemic metastasis remained unknown.
Recommendation for future research
Radiologists are advised that not every hemorrhagic cerebral lesion with laminar morphology is because of a thrombotic aneurysm, and similar morphology may occur due to intra-axial brain lesions including metastases.