Intracranial Ewing sarcoma with whole genome study

Area of Science:

• Neuro-oncology
• Genomic Medicine
• Pediatric Oncology

Background:

• Ewing sarcoma (ES) is exceptionally rare as a primary intracranial tumor.
• Recent reports suggest CNS embryonal tumors can exhibit ES-like genomic alterations.
• Intracranial tumors present diagnostic challenges, especially rare types.

Observation:

• A 13-year-old girl presented with headache and migraine due to an intracranial tumor.
• The tumor was located in the right middle cranial fossa, causing mass effect and impending transuncal herniation.
• Initial histopathology showed undifferentiated small round cell morphology, negative for Fli-1, and CD99-positive, mimicking CNS embryonal tumor, NOS.

Findings:

• Whole genome sequencing (WGS) identified an Ewing sarcoma (EWS)-Fli-1 gene fusion.
• Fluorescence in situ hybridization (FISH) confirmed the EWS-Fli-1 fusion.
• The diagnosis was revised from CNS embryonal tumor to intracranial Ewing sarcoma.

Implications:

• This case highlights the importance of advanced molecular diagnostic techniques for rare tumors.
• Genetic marker studies using FISH or next-generation sequencing (NGS) are crucial for accurate diagnosis.
• Accurate diagnosis of intracranial ES is vital for appropriate treatment and prognosis in pediatric oncology.