38-Year Delayed Spinal Leptomeningeal Dissemination of a Paediatric Pilocytic Astrocytoma: A Case Report

Introduction: Pilocytic astrocytoma (PA) is among the commonest primary intracranial tumours in children but has a low incidence among the adult population, and spinal occurrences are particularly infrequent. We report a spinal intradural extramedullary (IDEM) recurrence of this tumour a significant duration after initial treatment. Such a case is previously unreported in the literature. Case Summary: A 46-year-old female presented with a 3-month history of worsening back pain. Reduced sensation on the right side in L1, L2, and per rectum was found on examination. MRI displayed a L3 IDEM mass. Background was significant for childhood PA, debulked at age 8 and 13. Right L3 hemilaminectomy and subtotal resection was performed. The mass was found to be composed of pleomorphic astroglial cells and was glial fibrillary acidic protein-positive with a fusion between exon 16 of KIAA1549 and exon 9 of BRAF. A recurrence of pilocytic astrocytoma in the lumbar spine was diagnosed, over 38 years after previous treatment. Conclusion: This novel case of long-term leptomeningeal dissemination of cerebellar PA to the lumbar spine is unprecedented. The delayed dissemination of this tumour may warrant further molecular investigation of pilocytic astrocytoma to assess underlying predispositions for such a presentation.