[New in the current WHO classification (2020) for soft tissue sarcomas]

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• The World Health Organization (WHO) classification for soft tissue and bone tumors is continuously updated with new entities.
• Novel molecular findings are increasingly crucial for defining these neoplasms.
• Accurate classification is essential for diagnosis, prognosis, and treatment.

Purpose of the Study:

• To review and present newly identified entities and classifications in soft tissue and bone tumors.
• To highlight the significance of molecular alterations in tumor classification.
• To provide an overview of recent advancements impacting diagnostic criteria.

Main Methods:

• Review of recent literature and updates to the WHO classification system.
• Focus on molecular findings, including translocations, gene activations, and specific mutations.
• Integration of morphological, molecular, and biological data for tumor characterization.

Main Results:

• Introduction of translocation-positive tumors expanding the category of monomorphic mesenchymal neoplasias.
• Establishment of a separate chapter for undifferentiated small round cell sarcomas, emphasizing their distinct characteristics.
• Identification of tumors with GLI1 activation and NTRK-driven tumors, the latter offering therapeutic targets.
• Novel findings in rhabdomyosarcomas enabling more precise subtyping based on biological behavior.

Conclusions:

• The updated classification reflects significant progress in understanding the molecular basis of soft tissue and bone tumors.
• Molecular diagnostics are pivotal for defining new tumor entities and refining existing ones.
• These advancements facilitate more accurate diagnosis, targeted therapies, and improved patient outcomes.