Adamantinoma

Ted Scriven

Sept 15th, 2008

• Adamantinoma is a malignant bone tumour

Definition

• Rare• < 1% of primary bone tumours• Patents mostly 2nd and 3rd decade of life, but

wide range overall• Predilection for tibia - ~ 80% of cases• Usually occurs in diaphysis• Slight male predominance 1.25:1

Epidemiology

• Theory:

– Adamantinoma arises from aberrant nests of epithelial cells – this would explain why the high occurrence in the subcutaneous proximal tibia

• Theory:

– Osteofibrous dysplasia is benign precursor to adamantinoma

– ? 2 types – classic (>20yo) and differentiated (<20yo – transformed from OFD)

Etiology

• Slow growing therefore symptoms may be present for years

• Most common symptom: Pain• Occasionally palpable mass (due to

subcutaneous location)• 20% present with pathologic fracture

Clinical

• Xray:– Geographic

– Lucent

– Eccentric

– Usually, multiple lesions separated by areas of sclerosis– “soap bubbles”

– Cortical thinning

– No periosteal reaction

– Usually, no soft tissue mass

Radiological

• CT

– Not as useful as MRI

• MRI

– T1: low signal intensity

– T2: high signal intensity

Radiological

• osteofibrous dysplasia• fibrous dysplasia• ABC• chondromyxoid fibroma• chondrosarcoma

DDx

• Gross:– Lobulated

– Rubbery

– May have focal areas of hemorrhage and necrosis

– May have bone spicules and cysts filled with blood

Pathology

• Microscopic:– “Islands” or “nests” of epithelioid cells in a fibrous stoma

– May resemble fibrous dysplasia or osteofibrous dysplasia

– Minimal nuclear atypia, rare mitotic figures

– Immunohistochemical staining:• + for cytokeratins and vimentin

Pathology

• Wide resection or amputation• Radio-resistant• Chemo not shown to be effective

Treatment

• Prognosis depends on surgical margins

• Recurrence in 25 - 32% who do not undergo wide resection or amputation (< 10% by wide excision)

• Mets occur in up to 30%

• Mets usually in lungs or lymph nodes

• 85% survival at 10 yrs?

• Long term follow up very important as tumour is slow-growing

Prognosis

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