Clinical Lessons from Three Long-Term Survivors of Central Nervous System-Relapsed Pediatric Neuroblastoma: Diagnostic Challenges and Durable Disease Control Following Individualized Multimodal Therapy

Technical Summary: Clinical Lessons from Three Long-Term Survivors of CNS-Relapsed Pediatric Neuroblastoma

Problem Statement
Central nervous system (CNS) relapse in pediatric neuroblastoma is an uncommon but increasingly recognized pattern of recurrence associated with historically poor survival and significant diagnostic challenges. While systemic disease control has improved, CNS involvement remains a critical barrier to long-term survival. Current management lacks standardization, with evidence derived primarily from small, heterogeneous retrospective studies. A specific diagnostic dilemma exists: cerebrospinal fluid (CSF) cytology and flow cytometry often yield negative results despite radiologically evident disease, potentially leading to delayed diagnosis or inappropriate exclusion of CNS relapse. Furthermore, there is limited guidance on whether individualized multimodal therapy can achieve durable disease control in this setting.

Methodology
This study is a retrospective case series conducted at Beijing Tongren Hospital, Capital Medical University. The authors analyzed three pediatric patients with histopathologically confirmed neuroblastoma who subsequently developed CNS relapse.

• Inclusion Criteria: Patients required histopathological confirmation of neuroblastoma, radiological evidence of CNS relapse (intracranial parenchymal lesions, leptomeningeal enhancement, or spinal dissemination), and complete clinical, imaging, treatment, and follow-up data.
• Diagnostic Protocol: Diagnosis relied primarily on contrast-enhanced MRI. CSF evaluation (cytology and multiparameter flow cytometry) was performed when clinically indicated. Histopathological confirmation was obtained only in cases where surgical resection was performed.
• Treatment Strategy: Therapeutic decisions were individualized through multidisciplinary discussion involving oncologists, neurosurgeons, radiation oncologists, radiologists, and pathologists. All patients received a combination of systemic chemotherapy and repeated intrathecal chemotherapy (Methotrexate, Cytarabine, and Dexamethasone). Local therapies, including focal radiotherapy or surgical resection, were applied based on disease burden and response.
• Outcome Assessment: Patients were monitored via serial neuroimaging, neurological examination, and systemic surveillance. Radiological response was categorized as Complete Response (CR), Partial Response (PR), Stable Disease (SD), or Progressive Disease (PD).

Key Results

• Patient Cohort: The three patients (all male, aged 5 months to 5 years at initial diagnosis) developed CNS relapse 6 to 20 months after initial diagnosis. All presented with intracranial parenchymal disease accompanied by leptomeningeal dissemination; one patient also exhibited diffuse spinal involvement.
• Diagnostic Sensitivity: MRI successfully identified CNS relapse in all three patients. In contrast, CSF cytology and flow cytometry were positive in only one patient (Case 1). The other two patients had negative CSF studies despite unequivocal radiological evidence of disease, highlighting the limited sensitivity of CSF evaluation in this context.
• Treatment Outcomes: All three patients achieved durable disease control and remained alive at the latest follow-up (24 to 53 months post-relapse).
  • Two patients achieved Complete Radiological Remission (CR).
  • One patient maintained a sustained Partial Remission (PR) with stable neurological status for 48 months.
  • No patient experienced CNS progression during the observation period.
• Toxicity: Treatment-related toxicities were primarily hematological (Grades 2–4) and gastrointestinal (Grade I–II). No treatment-related mortality occurred, and no patient discontinued therapy due to complications.

Key Contributions
The paper provides three clinically significant observations derived from this case series:

1. Diagnostic Caution: Negative CSF studies (cytology and flow cytometry) should not be used to exclude CNS relapse when neuroimaging strongly suggests disease recurrence. MRI is the cornerstone of diagnosis and should not be superseded by negative laboratory findings.
2. Therapeutic Efficacy: Individualized multimodal therapy, integrating systemic chemotherapy, intrathecal chemotherapy (specifically the MTX/Cytarabine/Dexamethasone regimen), and selected local therapies (surgery or radiotherapy), can achieve prolonged disease control in carefully selected patients.
3. Management Framework: The authors propose a practical diagnostic algorithm emphasizing the integration of clinical assessment, prompt MRI, CSF evaluation (interpreted with caution), and multidisciplinary decision-making to facilitate timely treatment.

Significance and Claims
The authors claim that while larger multicenter studies are necessary to establish optimal treatment algorithms, this series demonstrates that long-term survival following CNS-relapsed neuroblastoma is achievable. The study challenges the historical view of CNS relapse as uniformly fatal by showing that early recognition via MRI and aggressive, individualized multimodal management can result in durable remission. The paper emphasizes that clinicians should maintain a high index of suspicion for CNS relapse in neuroblastoma patients with new neurological symptoms, regardless of prior treatment response or negative CSF findings. The findings suggest that the combination of intrathecal chemotherapy (to bypass the blood-brain barrier) and tailored local interventions represents a viable strategy for managing this rare complication.