Synonyms

Telangiectatic OS

Category

Bone

Behaviour

Malignant

Grade

High

Gender

Male

Tissue of Origin

Bone

Epidemiology

• 3–4% of all osteosarcomas
• Peak incidence in 2nd decade
• Aggressive variant - same treatment as conventional OS

Clinical Features

• Pain and rapid swelling
• Pathological fracture more common than conventional OS (25%)
• May feel fluctuant mimicking cyst or ABC
• Elevated serum alkaline phosphatase

Location

• Metaphysis of long Bones
• Distal femur most common
• Proximal tibia, proximal humerus
• Same distribution as conventional OS

Imaging

• Predominantly lytic 'bLow-out' lesion with minimal sclerosis
• Fluid-fluid levels on MRI - mimics aneurysmal Bone cyst
• Thin peripheral rim of Bone/tumour matrix
• Aggressive periosteal reaction and soft tissue mass (distinguishes from ABC)

Pathology

• Large blood-filled spaces separated by septa containing High-grade sarcomatous cells
• Osteoid must be identified in septal cells for OS diagnosis
• Markedly High-grade nuclear atypia
• Haemorrhagic grossly - easily confused with ABC intraoperatively

Genetics

• Complex karyotype
• TP53, RB1 alterations
• No specific defining alteration beyond conventional OS genetic profile

Treatment

• Neoadjuvant MAP chemotherapy - same as conventional OS
• Wide surgical resection
• Adjuvant chemotherapy based on histological response
• Excellent response to chemotherapy reported in some series

Prognosis

• 5-year survival 60–70% similar to conventional OS with modern chemotherapy
• Historically poor prognosis - now equivalent to conventional OS with modern treatment
• Pathological fracture at presentation does not necessarily worsen outcome
• Chemotherapy response predicts outcome as in conventional OS

Key Points

• Fluid-fluid levels on MRI mimic ABC - aggressive periosteal reaction and soft tissue mass are red flags for OS
• Never biopsy a suspected ABC before ruling out telangiectatic OS - confirm with MRI soft tissue component
• Treated identically to conventional osteosarcoma with MAP chemotherapy
• Osteoid must be identified in septal sarcomatous cells for correct diagnosis

Workup - Blood Tests

• FBC, U&E, LFTs, Bone profile - baseline and pre-chemotherapy
• Alkaline phosphatase, LDH - baseline

Workup - Local Imaging

• Plain radiograph - predominantly lytic 'bLow-out' lesion with thin rim, minimal sclerosis
• MRI primary site with gadolinium - critical: fluid-fluid levels mimic ABC, but aggressive periosteal reaction + soft tissue mass = OS
• CT chest/abdomen/pelvis - pulmonary and skeletal staging
• Bone scan or whole-body MRI - skip lesions and Bone metastases

Workup - Biopsy

• Core needle biopsy at sarcoma centre - en bloc excision of tract
• Histology: High-grade sarcoma in septal cells; MUST identify osteoid in septa for OS diagnosis
• Distinguish from ABC: telangiectatic OS has thin peripheral soft tissue rim of tumour

Workup - Staging

• CT chest - pulmonary metastases
• Bone scan or whole-body MRI - skeletal staging

Follow-up Summary

• Year 1: Post-operative visit within first 6 weeks (if primary surgery); 2-monthly clinical examination, CXR, plain films of primary site; annual blood biochemistry (U&E, LFT, Ca, PO4, Mg, HCO3); end of Year 1 - gonadal function (males: testosterone, LH, FSH; females: oestradiol, LH, FSH)
• Years 2–3: 3-monthly clinical examination, CXR, plain films of primary site; annual blood biochemistry; end of Year 2 - MUGA or ECHO
• Year 4: 6-monthly clinical examination, CXR, plain films of primary site; annual blood biochemistry; end of Year 4 - MUGA or ECHO
• Year 5: 6-monthly clinical examination, CXR, plain films of primary site; annual blood biochemistry
• Years 6–10: Annual clinical examination, CXR, plain films of primary site; annual blood biochemistry; end of Year 6 - MUGA or ECHO
• Limb function assessed at each visit using MSTS/TESS scores
• Annual xray of implant after 10 years