Glioblastoma multiforme metastasis outside the central nervous system: Three case reports and possible mechanisms of escape.

e13035 Background: Primary brain and central nervous system (CNS) tumor incidence is approximately 19 per 100,000 individuals per year in the United States (US) compared with 7 per 100,000 individuals worldwide. The most common intra-axial tumor is gliomas, which account for 32% of all primary CNS tumors and 80% of all malignant tumors of the CNS.The most common diffuse glioma is grade 4 astrocytoma (glioblastoma, GBM), which makes up 54% of diffuse glial tumors. GBM is also the most aggressive brain tumor with poor prognosis.GBM metastases outside the CNS are rare, so therapeutic experience with these types of tumors is limited. Methods: Herein, we present 3 GBM patients with extra-CNS metastasis. Results: One patient developed GBM metastasis in the lung and pleura 5 years after his GBM diagnosis had been confirmed. Another patient who underwent resection of the primary GBM developed disease that extended through the sphenoid to involve the orbit and skull and subsequently invaded the parotid gland and n...