Synonyms

• BCOR sarcoma
• BCOR-CCNB3 sarcoma

Category

Bone and soft tissue

Behaviour

Malignant

Grade

High

Gender

Male

Tissue of Origin

Unknown mesenchymal

Epidemiology

• Recently characterised molecular entity
• Predominantly children and young adults
• Male predominance (3:1)
• 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

Location

• Long Bones (femur, tibia) in Bone-primary cases
• Trunk 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
• Molecular characterisation revolutionised classification of small round cell sarcomas

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
• BCOR FISH (CCNB3 rearrangement) or RT-PCR for BCOR-CCNB3 fusion - confirmatory
• BCOR ITD by sequencing if FISH negative
• IHC: BCOR nuclear expression+, CD99 Variable, EWSR1/FUS FISH negative

Workup - Staging

• CT chest - pulmonary metastases
• Bone marrow trephine - bilateral iliac crests (Ewing-equivalent staging)
• Bone scan or PET-CT - systemic staging

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

• Follow Ewing sarcoma-equivalent protocol
• Year 1–2: 3–4 monthly clinical review + CXR; MRI primary site at 3 months then 6-monthly
• CT chest every 3–4 months for first 2 years (pulmonary metastasis surveillance)
• Years 3–5: 6-monthly clinical review + CXR; CT chest at 6-monthly intervals
• Years 6–10: Annual clinical review + CXR; CT chest annually
• Bone scan or whole-body MRI for Bone metastasis surveillance if symptomatic
• Discharge at 10 years with advice on self-monitoring
• Red flags: new pain at primary site, respiratory symptoms, new Bone pain