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Definitive diagnoses in neuro-oncology often require invasive procedures, such as surgical biopsies to obtain tissue for histopathologic and molecular interrogation. Patients with small lesions that may respond to nonsurgical treatments, such as chemoradiation, may nevertheless undergo surgery with potential risks to obtain diagnostic tissue. A means for noninvasively obtaining diagnostic information from brain tumors may improve patient care by limiting the need for surgery. Molecular evaluation of exosomes may provide such a means. Exosomes are small vesicles excreted from tumor cells that contain molecular information. Isolation of these vesicles from peripheral fluids, such as blood and urine, may provide diagnostic information for rendering a definitive diagnosis. Here, we review current clinical data for exosome-mediated brain tumor diagnostics.

Pediatric patients presenting with intramedullary spinal cord lesions often require specific diagnoses to guide their treatment plans. Though results from magnetic resonance imaging and lumbar puncture may narrow the differential diagnosis, these tests cannot always provide a definitive diagnosis. In such cases, spinal cord biopsy may be undertaken to provide a specific histopathologic diagnosis for guiding treatment. Data from the adult population show 24% of spinal cord biopsies can be nondiagnostic and the procedure may carry a 21% complication rate. Therefore, spinal cord biopsy may portend a similar high risk-to-benefit ratio in the pediatric population. Here, we review spinal cord biopsy cases scheduled for diagnosis, and not debulking, at a high volume pediatric referral center during a seventeen-year period. We report our experience with five patients who met our inclusion criteria. Due to the rarity of the procedure, statistically significant factors associated with improved diagnostic yield or peri-operative complication could not be identified. A definitive diagnosis which guided the post-operative treatment plan was obtained in four of our five patients. None of our patients developed post-operative motor deficits. However, these patients were susceptible to the same risks of open spine surgery, such as wound infections and spinal deformities. Our case series shows that intramedullary spinal cord biopsies may provide tissue for obtaining histopatholgic diagnoses. However, the potential risks of complication, and the possibility of obtaining nondiagnostic tissue, should be discussed with patients, families and their medical treatment teams., (Copyright © 2019. Published by Elsevier Ltd.)

Our patient's clinical history and preoperative radiographic evaluation suggested central nervous system (CNS) metastatic disease. Ultimately, final pathology revealed epithelioid glioblastoma (eGBM), a newly classified CNS primary tumor. This reinforces the importance of direct tissue sampling and including eGBM on the differential for young patients with histories of systemic cancer presenting with new CNS lesions., Competing Interests: None declared.