RESUMEN
Often in metastatic disease, biopsy confirmation of suspicious central nervous system (CNS) lesions is not mandated according to the American College of Radiology, International Radiosurgery Association, and the National Comprehensive Cancer Network. We present a case of an individual who was thought to have metastatic nonsmall cell lung cancer (NSCLC) T2aN0M1b with motor deficits and CNS metastasis to the left postcentral gyrus. The patient underwent biopsy of the primary lung mass confirming NSCLC. He subsequently underwent treatment with stereotactic radiosurgery (SRS) for presumed CNS oligometastatic disease and palliative chemotherapy. Two months after SRS, the patient had progression of CNS disease with new motor deficits. A magnetic resonance imaging revealed and enlarging mass in the previously radiated area. The patient underwent craniotomy with tumor resection and a second primary CNS tumor was discovered. That patient was downstaged from a Stage IV to a Stage IIB lung cancer with concomitant CNS primary.