ABC
Definition
Expansile pseudotumor of reactive hemorrhagic tissue arising in bone
- characterised by blood filled spaces separated by fibrous tissue
Types
Primary 50%
- arise de novo
Secondary 50%
- in association with other tumours
- probably secondary to haemorrhage into 1° tumour
- GCT / chondroblastoma / osteoblastoma / osteosarcoma
- often only small component
- should treat as underlying 1° tumour
Site
Metaphysis of long bones
- proximal humerus
- femur
- tibia
Posterior elements of vertebra
Epidemiology
Teenagers
- 80% occur in 10-20 year range
F>M
NHx
Pathological fracture rare
May resolve with fracture or skeletal maturity
X-ray
Multi-loculated lesion
- eccentric
- expansile
- cortical thinning
Bone Scan
Usually increased uptake
- centre may have decreased uptake
Exclude polyostotic disease
MRI
Haemosiderin content
- low to intermediate signal on T1 and T2
Fluid - Fluid levels
- due to sedimentation of RBC's & serum within the cavities
- patient must remain motionless for 10 minutes prior to the scan being performed
- allows time for sedimentation
DDx
Fibrous dysplasia
GCT
ABC
Infection
Unicameral Bone Cyst
Osteosarcoma
Pathology
Gross
Blood filled spaces with fibrous septa
Histology
Cells
- haemosiderin-laden macrophages
- multinucleated giant cells
Septa
- fibrous stroma
- small amounts of osteoid
Management
Non operative
Can observe majority
- need to avoid contact sports
Operative
Indications
Biopsy / diagnose
Potential instability - proximal femur / spine
Pain
Recurrent fracture / debilitating
Options
Currettage and bone graft
Allograft / Joint Replacement
Embolisation
Sclerotherapy
Currettage and bone grafting
Concept
Principles of biopsy approach
- confirm diagnosis on frozen section
- proceed to treatment
Indication
Must be able to preserve articular surface
Technique
Full and careful curettage
- intra-lesional treatment
- need to burr away all of lesion
- must take care as bone very thin
- areas of fracture not uncommon
- must beware growth plates in skeletally immature
- supplement with bone graft / bone marrow aspirate / PMMA
Resection and Allograft / TJR
Indications
Articular cartilage not salvageable
Selective Arterial Embolisation
Indications
- preoperative in spine lesions
Results
Rossi et al Skeletal Radiol 2010
- 55 cases both spine and appedicular with N butyl cryanoacrylate
- successful in 94% cases
- a second (25%) and third (14%) embolisation required
- 2 cases of skin necrosis and one transient paresis
Sclerotherapy
Results
Rastogi et al JBJS Br 2006
- percutaneous sclerotherapy with polidocanol in 72 patients under II guidance
- all had histological diagnosis prior to treatment
- 84.5% clinical response
- required between 1 and 5 treatments (average 3)
- 2 recurrences successfully treated with repeat sclerotherapy
Varshney et al Clin Orthop Relat Research 2010
- RCT of sclerotherapy v intralesional resection of 94 ABCs
- 3 year follow up
- 93% healing in sclerotherapy group with minimal complications
- 84% healing in operative group with 3 deep and 5 superficial infections and 2 growth disturbances
Spine
Papagelopoulos et al Spine 1998
- 52 cases in the spine
- treated with extralesional and intralesional excision with bone grafting
- 10% recurrence at 10 years, all presenting within 6 months post surgery
- 4 patients had postoperative radiotherapy
- 1 died of radiation related osteosarcoma, 1 of intraoperative bleeding
- now recommend preoperative embolisation