Metastatic lesions constitute a frequently occurring malignancy in the central nervous system (CNS) and play a significant role in clinical practice. Frequency estimations vary widely among published series owing to various institutional, diagnostic, and geographical biases that influence statistical evaluation (Henson and Urich, 1982) but there is general agreement that the overall incidence of CNS metastasis is increasing. This rising tendency might be due in part to increasing accuracy of reporting, but is probably secondary to a number of factors, including aging of the general patient population, longer overall survival of cancer patients as a result of advances in cancer diagnosis and improved management of primary cancers, and the increasing incidence of lung cancer and malignant melanoma, both of which exhibit high rates of dissemination to the CNS (Galicich et al., 1980). Estimates of the frequency of CNS metastasis based on autopsy studies are generally higher than estimates from other types of studies (Posner and Chernik, 1978; Chason et al., 1963; Aronson et al., 1964; Takakura et al., 1982). Incidence of intracranial metastases discovered at autopsy in patients who had systemic cancer, including hematologic malignancies, ranges from 11 to 35 percent (Lesse and Netsky, 1954; Posner and Chernik, 1978) and a large proportion of them (a quarter to one-third) are only diagnosed postmortem (Suki, 2004).