Epidural seeding in medulloblastoma: A rare presentation of tumor seeding.

Medulloblastoma is the most common malignant brain tumor in children, known for its high propensity to disseminate through the cerebrospinal fluid (CSF), particularly within the subarachnoid space. Leptomeningeal seeding, where tumor cells attach and proliferate within the leptomeninges, is a common manifestation. However, epidural seeding is an exceptionally rare occurrence, with very few cases documented in the literature. We present the case of an 8-year-old male diagnosed with anaplastic large cell medulloblastoma, who underwent complete tumor resection followed by radiotherapy and chemotherapy. Four years postoperatively, routine imaging revealed multiple thoracic spinal seedings and an epidural lesion at the S2-3 level. Surgical intervention confirmed the mass was confined to the epidural space, without intradural involvement, a notable finding given the rarity of this presentation. The mechanism behind epidural seeding remains unclear, though it was hypothesized that tumor cells may have been introduced during a lumbar puncture performed in the post-diagnosis period. This case contributes to the limited body of literature on epidural seeding in medulloblastoma, highlighting the importance of considering this rare phenomenon in long-term follow-up and surveillance of patients.