Intra-tumoral hemorrhage after endoscopic third ventriculostomy in a child with WNT-activated medulloblastoma: case report and literature review.

Intratumoral hemorrhage is a known complication of cerebrospinal fluid (CSF) drainage surgeries, such as ventriculoperitoneal shunts or external ventricular drainage, which are usually associated with upward herniation of the posterior fossa contents. In contrast, this is extremely rare after an endoscopic third ventriculostomy (ETV). This technique should drain the CSF in a more physiological way by limiting the pressure gradient between the infratentorial and supratentorial compartments, thus avoiding upward herniation of the tumor and intratumoral hemorrhage. Only three cases of intratumoral hemorrhage after ETV have been reported in the literature. Here, we describe a 9-year-old boy affected by hydrocephalus secondary to a large posterior fossa tumor who presented intratumoral hemorrhage after ETV. He required urgent hematoma evacuation and tumor removal. Histological and molecular diagnosis was WNT-activated medulloblastoma, a tumor associated with an increased risk of hemorrhage.