Spinal Leptomeningeal Dissemination of Pineoblastoma in a 16-Year-Old Girl: A Case Report and Review of the Literature.

Pineoblastoma is a rare and highly aggressive embryonal tumor of the pineal region, predominantly affecting children and adolescents. It is classified as a CNS WHO grade 4 tumor and is characterized by a high risk of cerebrospinal fluid dissemination. Although leptomeningeal spread is a recognized feature of this tumor, spinal metastatic involvement at diagnosis remains uncommon and indicates high-risk disease. We report the case of a 16-year-old girl with no relevant past medical history who presented with a two-week history of sleep disturbances, right-sided strabismus, and projectile vomiting. Brain MRI demonstrated a heterogeneous pineal region mass measuring approximately 28 × 26 mm, associated with triventricular hydrocephalus. The patient underwent endoscopic ventriculocisternostomy and stereotactic biopsy. Histopathological and immunohistochemical findings confirmed the diagnosis of pineoblastoma. Staging spinal MRI revealed multiple dorsal spinal leptomeningeal nodules, consistent with CSF dissemination and spinal drop metastases. Given the rarity of pineoblastoma and the absence of a universally established pineoblastoma-specific therapeutic protocol, the case was discussed with an international pediatric neuro-oncology expert. Based on this expert recommendation, the patient was treated using a high-risk medulloblastoma-derived regimen. She received craniospinal irradiation with weekly vincristine, followed by adjuvant chemotherapy with cisplatin, cyclophosphamide, and vincristine according to an ACNS0332-based approach. At three months after completion of treatment, follow-up MRI showed complete regression of the spinal metastatic lesions and a small residual cystic lesion in the pineal region. Clinically, the patient showed marked improvement, particularly in oculomotor function. This case highlights the importance of systematic craniospinal staging at diagnosis in pineoblastoma and illustrates the potential value of early multidisciplinary and multimodal management in metastatic disease. At nine months of follow-up, the patient remained clinically stable, without evidence of spinal disease progression on serial imaging. However, this follow-up remains limited, and long-term clinical and radiological surveillance is essential because of the high risk of recurrence.