BCOR-Rearranged Sarcoma
Synonyms: BCOR sarcoma, BCOR-CCNB3 sarcoma, undifferentiated round cell sarcoma with BCOR::CCNB3 fusion
Classified as Ewing-like sarcoma - shares histological and some clinical features with Ewing sarcoma
Quick Facts
Behaviour
Malignant
Category
Bone and soft tissue
Grade
High
Synonyms
- BCOR sarcoma
- BCOR-CCNB3 sarcoma
- undifferentiated round cell sarcoma with BCOR::CCNB3 fusion
Category
Bone and soft tissue
Behaviour
Malignant
Grade
High
Gender
Male (3:1)
Tissue of Origin
Unknown
Epidemiology
- Recently characterised molecular entity
- Predominantly children and young adults
- 4% of undifferentiated round cell sarcomas
- Included in Ewing-like sarcoma group
Clinical Features
- Pain and swelling at affected site
- Periosteal reaction in bone lesions
- Rapidly growing mass
- Systemic symptoms uncommon
- Usually metastasises to the lung
Location
- Bone > soft tissue > vicera
- Long bones in bone-primary cases
- Spine and axial skeleton
- Soft tissue (trunk, extremities)
Imaging
- Aggressive permeative lytic bone destruction
- Soft tissue mass with onion-skin periosteal reaction
- MRI: large heterogeneous mass with oedema
- Resembles Ewing sarcoma radiologically
Pathology
- Small round blue cell tumour - undifferentiated
- BCOR-CCNB3 fusion or BCOR internal tandem duplication (ITD)
- Variable CD99 expression
- BCOR nuclear expression by IHC
Genetics
- BCOR-CCNB3 fusion (paracentric inversion of chromosome X)
- BCOR ITD (internal tandem duplication)
- Negative for EWSR1/FUS rearrangements
- Molecular testing required for diagnosis
Treatment
- Ewing-like treatment protocols used (VAC/IE alternating)
- Surgical resection after neoadjuvant chemotherapy
- Radiotherapy for unresectable lesions
- High-dose chemotherapy with stem cell rescue for high-risk disease
Prognosis
- Prognosis appears similar to or slightly better than Ewing sarcoma
- 5-year survival 70–80% for localised disease
- Distant metastasis (lungs, bone) worsens prognosis
- Data limited due to rarity
Key Points
- Classified as Ewing-like sarcoma - shares histological and some clinical features with Ewing sarcoma
- BCOR FISH or RT-PCR required for definitive diagnosis
- Treated with Ewing sarcoma protocols pending more specific data
Workup - Blood Tests
- FBC, ESR, CRP - baseline
- LDH - elevated in systemic disease; prognostic marker
- U&E, LFTs - pre-chemotherapy baseline
- Coagulation screen
Workup - Local Imaging
- Plain radiograph
- MRI with contrast
Workup - Biopsy
Core needle biopsy at sarcoma centre - send fresh tissue for molecular testing
Workup - Staging
- CT chest - pulmonary metastases
- PET-CT - systemic staging
- Bone marrow aspirate in specific cases
Workup - Other
- MDT at specialist sarcoma centre mandatory
- Treat per Ewing sarcoma protocol pending specific trial data
- Echocardiogram baseline prior to anthracycline chemotherapy
Follow-up Summary
- 1
Follow Ewing sarcoma-equivalent protocol
Ewing's Sarcoma / Rhabdomyosarcoma - Localised Post Primary Treatment
Medical disclaimer
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