β£Description of Aneurysmal bone cystSkeletally immature - < 20 years old in 75%!L: Metaphyseal, EccentricA: Lytic, expansile "wider than diameter of physis", Lobulated "soap bubble"R: narrow zone, no periosteum changesM: lytic, some sclerosisβ£What is the gene involved in ABC?Ubiquitin Specific Protease (USP-6)(Paget is Ubiquitin Binding Protein Sequestosome)β£What are the types of ABC?Primary vs Secondary ABCCan be secondary inGCT, CMF, NOF, FDβ£Where are the most common areas?Humerus, leg, pelvis, spinePosterior triangle of spine - 25%! (cf. GCT grows in the vertebral body!)Calcaneumβ£Classification of ABC?Capanna Classification - note does not abut the joint surfaceType 1 = Central metaphysealType 2 = Involves entire segment of boneType 3 = Eccentric metaphyseal locationType 4 = Subperiosteal extensionType 5 = Meta-diaphysial locationβ£Investigation of ABC? What is on histology?Will need biopsy TRO Telengiectatic OsteosarcomaJPO review 2006cottalorda2006.pdf317.9KBMRI - Fluid Fluid levels Histology - "Cavernous" blood filled space without endothelial lining #histoβ£Management of ABC?Symptomatic ABC (without fracture)Aggressive curettage with adjuvant and bone graftingAcute pathological fracture of ABCNon operative fracture management until fracture has healed. Then manage as aboveLocal recurrence up to 25%Curretage, adjuvant, grafting