NCMP-18. A CASE OF METASTATIC GLIOBLASTOMA MULTIFORME

Abstract Glioblastoma multiforme (GBM) is the most common primary brain tumor and rarely causes metastasis. We present a case of a 43-year-old female who developed tingling and heaviness in her right lower extremity in March 2023. This sensation progressed to involve her entire right hemi-body over the next two months. She presented to the emergency department where an MRI show a large left frontal parietal mass measuring 5.2x3.7x3.7cm with significant mass effect. She underwent surgical resection and surgical pathology showed IDH1-mutant R132H, retained ATRX, MGMT promoter mutation, and ki-67 of 80%. She received 6 weeks chemoradiation and then started maintenance temozolomide at 150mg/m2. Temozolomide was increased to 200mg/m2 for cycle 3 maintenance. In March 2024, she presented to the hospital with pain radiating down her legs and saddle anesthesia. MRI lumbar spine showed infiltrating osseous mass at S1 and S2 and bilateral sacral ala with anterior and posterior extraosseous invasion, invading the spinal canal resulting in moderate to severe spinal canal narrowing and compression of the sacral nerve roots. She underwent biopsy of the lesion which showed IDH wildtype metastatic GBM. She also underwent lumbar puncture and cerebrospinal fluid cytology was negative. She experienced pancytopenia limiting chemotherapy options. In April 2024, she underwent PET scan which showed hypermetabolic epidural soft tissue in spinal canal at L5-S1 level, widespread hypermetabolic skeletal lesions, tiny left cervical level 4 lymph node, small hypermetabolic right hilar, aortocaval, left retroperitoneal nodes and a tiny left common iliac node. The incidence of extracranial metastasis is 0.4-2.0% with less than 25 reported cases of bone marrow spread. This is thought to be rare due to the absence of lymphatics within the brain and the limited survival associated with GBM. This metastasis may occur through vascular invasion, perineural spread, lymphatics, direct invasion, or iatrogenic spread into soft tissues.