Aneurysmal Bone Cyst

 

ABC Proximal HumerusABC Distal Femur

 

Definition

 

Expansile pseudotumor of reactive hemorrhagic tissue arising in bone

 

Characterised by blood filled spaces separated by fibrous tissue

 

Site

 

Metaphysis of long bones

- proximal humerus

- femur

- tibia

 

Posterior elements of vertebra

 

Epidemiology

 

Teenagers

- 80% occur in 10-20 year range

- mean age 14 years

 

Female >Male

 

Symptoms

 

Pain

Mass

Pathological fracture

 

Natural history

 

Pathological fracture rare

May resolve with fracture or skeletal maturity

 

Types

 

Primary 50%

- arise de novo 

 

Oliveira et al Am J Pathol 2004

- rearrangements of USP6 and/or CDH11 genes in 70% of cases

- absent in secondary ABC

 

Secondary / ABC like areas in other tumors 50%

- probably secondary to haemorrhage into primary tumour

- Giant cell tumour / chondroblastoma / osteoblastoma / osteosarcoma

- treat as underlying primary tumor

 

X-ray

 

Multi-loculated expansile lesion with cortical thickening

Often fail to make definitive diagnosis on xray

 

ABC humerusABC ankleABC fibula

 

MRI 

 

Usually difficult to determine UBC from ABC

- cystic lesions

- haemosiderin content - low to intermediate signal on T1 and T2

- borders and septae enhance with contrast

 

Gruenewald et al Br J Radiol 2023

- 36 patients with UBC or ABC

- fluid fluid levels / septation seen in both on MRI

- arterial feeders on MRA helped differentiate some ABC's

 

ABC ankle mri 1ABC ankle MRI 2ABC distal femur MRI

 

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

- can also be seen in UBC

 

 ABC MRI fluid fluid levelsMRI ABC distal femur

 

CT

 

ABC CT ankle

 

ABC clavicleABC clavicle CT

ABC medial clavicle

 

Bone Scan

 

Usually increased uptake

Exclude polyostotic disease

 

DDx

 

Fibrous dysplasia / GCT / Unicameral Bone Cyst / Infection / Osteosarcoma

 

Pathology

 

https://www.pathologyoutlines.com/topic/boneabc.html

 

Gross pathology

 

Blood filled spaces with fibrous septa

 

Histology

 

Cells

- haemosiderin-laden macrophages

- multinucleated giant cells

 

Septa

- fibrous stroma

- small amounts of osteoid

 

Genetics

- USP6 rearrangements

- no expression of H3G34W (GCT)
- no expression of H3K36M (chondroblastoma)

- no expression of SATB2 (osteosarcoma)

 

Management

 

Nonoperative Management

 

Observation

 

Avoid contact sports

 

Interventional radiology

 

Sclerotherapy

Embolization

Injection of demineralized bone matrix / bone marrow

 

Results

 

Cruz et al Eur J Orthop Surg Traumatol 2021

- systematic review comparing sclerotherapy to embolization

- 13 studies with 416 patients

- recurrence embolization 19%

- recurrence sclerotherapy 6%

 

Sclerotherapy

 

Rai et al J Orthop 2022

- injection of sequential intralesional percutaneous polidocanol in 43 patients

- complete resolution in 37/43 at one year, and 43/43 at two years

 

Rastogi et al JBJS Br 2006

- 72 patients with ABC with mean age 15

- treated with percutaneous intralesional 3% polidocanol

- average number of injections of 3 (range, 1 - 5)

- 10/72 patients cured with single injection

- 2/72 (3%) had recurrence at 2 years, successfully treated again with sclerotherapy

 

Selective Arterial Embolisation

 

Indications

- difficult to reach locations

- spine / pubis / sacrum

 

Results

 

Rossi et al Int Orthop 2017

- 102 cases of ABC treated with arterial embolization with 7 years follow up

- feasible in 88 (86%) of patients with a feeding artery

- overall 82% success

- successful in 57% with one embolization, 19% two embolizations, 6% three embolizations

- 18% recur and require surgical intervention

 

Autogenous bone marrow / Demineralized bone matrix

 

Docquier et al JBJS Am 2005

- 13 aneurysmal bone cysts

- small incision

- injection of demineralized bone and autologous bone marrow

- healing in 11/13

 

Andreani et al Stem Cells Int 2020

- 42 ABCs treated with injection of BMC (bone marrow concentrate)

- 32/42 healed with 1 injection

- 7/10 healed with second injection

- 2/3 healed with third injection

 

Operative Management

 

Indications

 

Failure minimally invasive treatment

Joint space threatened

Weight bearing joints

 

Options

 

Currettage and bone graft

Currettage / bone graft / fixation

Allograft / Joint Replacement

 

Results

 

Strohm et al Eur J Trauma Emerg Surg 2023

- meta-analysis of 163 studies

- currettage had 91% healing and 22% recurrence

- currettage and autologous cancellous bone graft had 96% healing and 15% recurrence

 

Lin et al CORR 2008

- case series 53 patients

- closer to physis = higher recurrence rate

 

Currettage and bone grafting

 

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

 

ABC ankleABC CT ankleABC ankle bone graft ORIF

 

Results

 

Cevolani et al J Tissue Eng Regen Med 2021

- 239 patients treated with curettage and bone graft

- healing in 177/239 (74%) at 42 months

 

Syvanen et al Scand J Surg 2018

- 18 cases treated with curettage and bioactive glass

- 2/18 (11%) recurrence

 

Currettage / Bone graft / Fixation

 

ABC Currettage and Bone GraftingABC Bone Grafting

 

ABC Grade 3ABC Grade 3 Bulk Structural Allograft

 

Resection and arthroplasty

 

Indications

 

Articular cartilage not salvageable