Systemic metastasis of medulloblastoma through ventriculoperitoneal shunt: report of a case and critical analysis of the literature.

An unusual case of medulloblastoma metastasizing through a ventriculoperitoneal shunt to the scrotum in a child with a hydrocele is presented. A review of the literature disclosed 160 cases of medulloblastoma with systemic metastases, 30 (18.7%) of them having undergone systemic shunts. Analysis of the distribution patterns of the metastases in relation to the shunt type revealed that shunts had probably provided the route of systemic spread in no more than 11 cases (6.9%). Only one of these cases had no intracranial tumor at autopsy, suggesting that the outcome was probably worsened by the systemic metastases through the shunt. In contrast, five patients had intraaxial tumor recurrence that largely determined the outcome. In the remaining five cases, information concerning the tumor within the central nervous system was not available, and it remains speculative whether these patients could have survived longer without the shunts. It is concluded that the chance of medulloblastoma metastasizing through cerebrospinal fluid shunt is quite small and has an even smaller chance of adversely affecting the final outcome of the medulloblastoma patient. Consequently, in our opinion there should be no contraindication to precraniotomy shunting if required in such patients.