Intracranial Ewing sarcoma: four pediatric examples.

Area of Science:

• Neuro-oncology
• Pediatric oncology
• Skeletal and soft tissue sarcomas

Background:

• Ewing sarcoma typically originates in bone, distinct from central nervous system (CNS) embryonal tumors.
• Primary intracranial Ewing sarcoma is exceptionally rare, often dural-based, with most CNS cases being secondary to metastasis.
• This study focuses on rare instances of primary Ewing sarcoma within the cranial vault.

Observation:

• Four pediatric patients (ages 5-16) with solitary, primary intracranial Ewing sarcoma were identified over 21 years.
• Tumor presentations varied, including large masses, soft tissue involvement, and incidental findings, with three cases showing clear bony involvement.
• All four tumors exhibited the characteristic EWSR1 gene rearrangement, confirming the diagnosis.

Findings:

• The EWSR1 gene mutation is a definitive diagnostic marker, differentiating Ewing sarcoma from other embryonal CNS tumors.
• Treatment outcomes were variable, with one patient experiencing metastatic disease and death, while others achieved long-term disease-free survival or were alive and well post-therapy.
• Complete surgical resection followed by an appropriate Ewing sarcoma treatment regimen is crucial.

Implications:

• Accurate diagnosis via EWSR1 mutation testing is critical for appropriate management of primary intracranial Ewing sarcoma.
• Despite rarity, primary intracranial Ewing sarcoma can be effectively treated, with potential for long-term survival.
• This case series contributes to understanding the clinical presentation and outcomes of this rare pediatric CNS malignancy.