Genomic Insights Into High-Grade Infarct-Associated Bone Sarcomas

Area of Science:

• Oncology
• Genomics
• Skeletal Biology

Background:

• Infarct-associated sarcomas are rare bone tumors with poorly understood genetic characteristics.
• High-grade undifferentiated pleomorphic sarcomas (UPS) of bone are typically treated with surgery and chemotherapy.

Purpose of the Study:

• To conduct a detailed clinicopathologic and genomic analysis of intraosseous sarcomas arising from bone infarcts.
• To understand the genetic landscape and identify potential therapeutic targets in these rare bone sarcomas.

Main Methods:

• Next-generation sequencing (523 genes) and whole-genome SNP Microarray (OncoScan CNV) for mutation and copy number alteration analysis.
• Assessment of genomic instability using homologous recombination deficiency (HRD) metrics.
• Fluorescence in situ hybridization (FISH) and immunohistochemistry for validation.

Main Results:

• Genomic analysis revealed significant complexity and high HRD scores (32-57) in all 6 cases.
• Common alterations included chromosome 12 abnormalities (4/6 cases), homozygous CDKN2A/B deletion (6/6 cases), and MDM2 amplification (2/6 cases).
• Notable mutations included H3-3A, HRAS, DNMT3A, NF2, PIK3CA, POLE, and TP53.

Conclusions:

• High-grade infarct-associated sarcomas of bone exhibit high genomic complexity and HRD, similar to osteosarcoma.
• These sarcomas may differ from conventional osteosarcoma with potentially fewer TP53 mutations and more frequent CDKN2A/B deletions.
• The distinct mutation spectrum suggests unique disrupted pathways in infarct-associated bone sarcomas.