Cerebrospinal Fluid Seeding Versus Inflammation in Setting of Ventriculoperitoneal Shunt as a Potential Cause for Distant Recurrence of Glioblastoma.

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults with a median survival of approximately 15 months, despite treatment, with most patients experiencing recurrence within 9 months of resection. The propensity of recurrence in GBM exemplifies the fatal course of the disease and remains an underlying area of study as novel instances of recurrence are encountered. The authors present a unique case of a 31-year-old male patient with a history of cerebellomedullary junction astrocytoma who later developed a supratentorial GBM followed by recurrence centered around a preexisting ventriculoperitoneal catheter and located in the hemisphere contralateral to his first GBM. Each of these lesions was initially thought to represent de novo glial neoplasms because of the absence of intervening T2 fluid-attenuated inversion recovery signal change between each lesion. However, next-generation sequencing using the GlioSeq™ platform revealed similar mutational profiles in both GBMs, suggesting an alternative method of migration of tumor cells to the shunt catheter site, and a local inflammatory environment likely triggering recurrence. This study concludes that in rare instances, in the presence of dormant glioma cells, intracranial foreign bodies may promote an inflammatory microenvironment that may activate tumorigenesis.