Ventriculoperitoneal shunt-associated cystic lesion with perilesional cerebral edema 45 years after placement for posterior fossa tumor: A case report

Background: Ventriculoperitoneal (VP) shunts are widely used to treat hydrocephalus in children with posterior fossa tumors. While many patients gain shunt independence after tumor control, indwelling shunts are often not removed. Shunt-related intracranial cysts are extremely rare and typically develop along the intracranial catheter tract within days to several years after shunt insertion; to date, the longest reported interval has been 19 years. Here, we report a case a cystic lesion with marked perilesional edema developing 45 years after childhood VP shunt placement for tumor-related hydrocephalus. Case Description: We report the case of a 58-year-old man who presented with acute severe left-sided hemiparesis. At the age of 13 years, he underwent resection of a posterior fossa ependymoma, VP shunt placement, and whole-brain radiotherapy. Neuroimaging revealed a large right frontal low-density lesion with vasogenic edema and a cystic cavity surrounding the intracranial shunt catheter. Retrospective review of magnetic resonance imaging performed 3 months earlier showed a smaller preexisting cyst at the same site. The shunt catheter was removed without resistance, and the membranous material adhering to the distal tip caused partial intraluminal obstruction. Postoperatively, the hemiparesis improved markedly; follow-up imaging demonstrated resolution of the edema and reduction in the cyst size. As hydrocephalus did not recur, shunt reinsertion was not required. Conclusion: This case represents the longest latency reported in the literature for VP shunt-related intracranial cyst formation, occurring 45 years after shunt implantation, exceeding the previously reported maximum interval of 19 years. The acute symptoms closely resemble stroke or infection, underscoring the diagnostic challenge. Clinicians should be vigilant of such delayed complications even decades after shunt placement.