Direct spread of medulloblastoma in adjacent extrameningeal tissues.

A case of a medulloblastoma with extensive intradural dissemination and direct tumour spread from a lumbosacral deposit in the pelvis is presented. A review of the literature revealed six similar cases. In all of them direct invasion of contiguous structures occurred at sites of secondary deposits. Two predilection site were identified: 1. The anterior fossa with tumour invasion of the paranasal air sinuses. 2. The lumbosacral spine with tumour extension into the retroperitoneum and pelvis. Generally, this unusual mode of tumour spread indicates a final stage in the course of the disease. The possible pathogenesis is discussed.