AdamantinomaTed Scriven

Sept 15th, 2008

Adamantinoma is a malignant bone tumourDefinition

Rare< 1% of primary bone tumoursPatents mostly 2nd and 3rd decade of life, but wide range overallPredilection for tibia - ~ 80% of casesUsually occurs in diaphysisSlight male predominance 1.25:1Epidemiology

Theory: Adamantinoma arises from aberrant nests of epithelial cells this would explain why the high occurrence in the subcutaneous proximal tibiaTheory:Osteofibrous dysplasia is benign precursor to adamantinoma? 2 types classic (>20yo) and differentiated (

Slow growing therefore symptoms may be present for yearsMost common symptom: PainOccasionally palpable mass (due to subcutaneous location)20% present with pathologic fracture

Clinical

Xray:GeographicLucentEccentricUsually, multiple lesions separated by areas of sclerosissoap bubblesCortical thinningNo periosteal reactionUsually, no soft tissue massRadiological

CTNot as useful as MRI

MRIT1: low signal intensity T2: high signal intensityRadiological

osteofibrous dysplasiafibrous dysplasiaABCchondromyxoid fibromachondrosarcoma DDx

Gross:LobulatedRubberyMay have focal areas of hemorrhage and necrosisMay have bone spicules and cysts filled with bloodPathology

Microscopic:Islands or nests of epithelioid cells in a fibrous stomaMay resemble fibrous dysplasia or osteofibrous dysplasiaMinimal nuclear atypia, rare mitotic figuresImmunohistochemical staining:+ for cytokeratins and vimentin

Pathology

Wide resection or amputationRadio-resistantChemo not shown to be effectiveTreatment

Prognosis depends on surgical marginsRecurrence 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 nodes85% survival at 10 yrs?Long term follow up very important as tumour is slow-growingPrognosis

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