Intramedullary metastasis in a case of vermian medulloblastoma

Medulloblastoma is one of the commonest primary CNS malignancies in children. Leptomeningeal dissemination and distant metastasis have been associated with medulloblastoma, but intramedullary metastases are very rare. CSF cytology and contrast-enhanced MRI are the main modalities used to diagnose leptomeningeal dissemination. However, intramedullary metastases are best picked up with contrast-enhanced axial sequences on MR imaging. In this report, a patient with medulloblastoma who developed intramedullary metastasis is described. The role of imaging and CSF cytology in diagnosing the spread along the CSF pathways is reviewed. Allusions are made to the possible mechanism of intramedullary metastasis in these tumors.