Synonyms

• Adamantinoma of long Bones
• classic adamantinoma

Category

Bone

Behaviour

Malignant

Grade

Variable

Gender

Males

Tissue of Origin

Epithelial (unknown origin)

Epidemiology

• Rare, <1% of primary Bone tumours
• Wide age range with peak incidence in 2nd–4th decades
• Ranges from OFD-like adamantanoma, classic adamantanoma and dedifferentiated adamantanoma

Clinical Features

• Slowly progressive pain and swelling over years
• Palpable anterior tibial mass in most cases
• Rare pathological fracture
• Slow-growing but Malignant course

Location

• Tibia in 90% of cases (anterior cortex)
• Fibula in 10%
• Rarely other long bones or axial skeleton

Imaging

• Eccentric cortical lytic lesion with soap-bubble appearance
• Anterior tibial bowing
• Multifocal lesions can be present in same bone
• MRI shows lobulated low-signal mass

Pathology

• Biphasic tumour: epithelial nests in fibrous stroma
• Four histological subtypes: basaloid, tubular, spindle cell, squamoid
• Keratin-positive epithelial component
• Associated osteoFibrous dysplasia in periphery

Genetics

Positve for vimentin, keratin, p63

Treatment

• Wide local excision with adequate margins
• Limb salvage feasible in most cases
• Amputation for extensive local disease
• Fibular reconstruction may be required

Prognosis

• Metastasis in 12-30% (lungs, lymph nodes)
• Late recurrence and metastasis possible (>10 years)
• Juvenile form (OFD-like) has better prognosis with recurrence of 20%

Key Points

• Unique biphasic epithelial-fibrous tumour of bone
• Tibial predilection is virtually diagnostic
• Cytokeratin positivity confirms epithelial component
• Ostefibrous dysplasia-like variant may precede or coexist with classic form

Workup - Blood Tests

• FBC, U&E, LFTs - pre-operative baseline
• Bone profile - alkaline phosphatase
• Coagulation screen

Workup - Local Imaging

• Plain radiograph
• MRI with contrast of whole bone

Workup - Biopsy

• Core needle biopsy at sarcoma centre
• Immunohistochemistry: cytokeratin (AE1/AE3, MNF116) positive - confirms epithelial component
• EMA, p63 positive; S100 negative
• Exclude metastatic carcinoma: clinical and radiological correlation essential

Workup - Staging

• CT chest for pulmonary and lymph node staging
• Whole-body imaging if metastatic disease suspected

Workup - Other

MDT review with sarcoma specialist centre

Follow-up Summary

• Post-operative review at 6 weeks
• Year 1–2: 3–4 monthly clinical review + CXR and xray primary site
• Years 3–5: 6-monthly clinical review + CXR and xray primary site
• Years 6–10: Annual clinical review + CXR and xray primary site
• Discharge at 10 years - late recurrence and metastasis possible beyond 10 years; advise self-monitoring
• Imaging: CT chest for pulmonary surveillance (lungs and lymph nodes are metastatic sites)
• Red flags prompting early review: new tibial pain, expanding mass, pulmonary symptoms