Ewing sarcoma and Ewing-like tumors.

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Ewing sarcoma (ES) and Ewing-like sarcomas are aggressive round cell neoplasms primarily affecting children and young adults.
• Recent molecular discoveries have led to a reclassification of these tumors, reducing the undifferentiated round cell sarcoma category.
• Current classifications include ES, EWSR1 gene fusion sarcomas, CIC-rearranged sarcomas, and BCOR-rearranged sarcomas.

Purpose of the Study:

• To review the current classification of Ewing sarcoma and Ewing-like sarcomas.
• To highlight the importance of molecular alterations in differentiating these entities.
• To guide diagnostic and management strategies for these rare tumors.

Main Methods:

• Review of morphologic, immunohistochemical, and molecular findings.
• Discussion of diagnostic challenges and differential diagnoses.
• Emphasis on the role of next-generation sequencing (NGS) for molecular classification.

Main Results:

• Morphologic features can predict underlying molecular alterations in CIC-rearranged and BCOR-rearranged sarcomas.
• Accurate classification relies on a combination of morphology, immunohistochemistry, and molecular data.
• Significant differences in chemotherapy response and survival exist among these entities.

Conclusions:

• Accurate classification of Ewing sarcoma and Ewing-like sarcomas is crucial due to differing treatment responses and prognoses.
• Molecular diagnostics, particularly NGS, are essential for precise classification.
• Referral to specialized centers is recommended for optimal diagnosis and management of these rare cancers.