List the clinical features.
acute or subacute onset of symptoms due to rapid tumor growth
Focal neurological deficits
Describe the imaging findings.
Imaging: well-circumscribed tumors at the junction of gray and white matter and/or watershed areas of the arterial system
Large metastases: ring enhancement due to central necrosis
Small metastases: homogeneous enhancement
If the primary tumor is unknown: whole-body contrast CT and/or PET scan
If no primary tumor is found or if the tumor is not surgically accessible: biopsy of the brain metastasis