Pathology of cerebral metastases.

Important pathologic features of cerebral metastases include the route of spread of tumor cells to the brain, differences among metastases based on location in dura mater, leptomeninges, and brain parenchyma, differences based on primary tumor site, both known and unknown, the means of spread of metastases within the brain, and the brain's reactions to metastases. Immunohistochemistry and electron microscopy are increasingly used in the pathologic evaluation of cerebral metastasis.