Extraneural metastases of infratentorial glioblastoma multiforme to the peritoneal cavity.

This report describes two autopsy-proven cases of a rare complication of infratentorial glioblastoma multiforme (GBM): metastatic seeding of the peritoneal cavity through ventriculoperitoneal (VP) shunts. Patient 1 was a 13-year-old boy with a pontine GBM, and Patient 2 was a 9-year-old girl with a thoracolumbar spinal cord GBM. Autopsy of both patients demonstrated leptomeningeal gliomatosis encasing the spinal cord and basal structures of the brain, in addition to peritoneal and omental metastases. The pattern of abdominal metastasis seen in these patients is typical of tumors that directly seed the peritoneal cavity and implicates the VP shunt as the vehicle of extraneural spread. Although a rare occurrence, extraneural metastases should be sought in patients with glioma with VP shunts who demonstrate increased abdominal girth, unexplained weight gain, or persistent abdominal pain.