Benign Bone Tumours

Lucent Lesions

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

 

ABC Proximal HumerusABC Distal Femur

 

Bone Scan

 

Usually increased uptake

- centre may have decreased uptake

 

Exclude polyostotic disease

 

MRI 

 

Haemosiderin content

- low to intermediate signal on T1 and T2

 

ABC MRI Distal Femur

 

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

 

 ABC Fluid Fluid Levels MRI

 

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

 

ABC Currettage and Bone GraftingABC 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

 

ABC Grade 3ABC Grade 3 Bulk Structural Allograft

 

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

 

Adamantinoma

Definition

 

Rare low-grade malignant tumour

- cell of origin unknown

 

Epidemiology

 

Usually second or third decade of life

 

Site

 

90% diaphysis of tibia 

 

Mandible

 

X-ray

 

Most common anterior cortex of tibia

 

Soap-bubble appearance

 

Eccentrically located

- well circumscribed

- slightly expansile

- cortical thickening

- little or no periosteal reaction

- can have late deformity

 

DDx

 

Fibrous dyplasia

Osteofibrous dysplasia / Ossifying fibroma / Osteosarcoma

Giant cell tumour

ABC

Chondrosarcoma / CS

Infection / osteomyelitis

Unicameral bone cyst

 

Diaphyseal lesion / HALFEE

- Histiocytoma

- Adamantinoma

- leukemia

- FD

- EG

- Ewings

 

Pathology

 

Two distinctly different components

 

1.  Epithelial origin 

- composed of squamous cells and epithelial pearls 

 

2.  Mesenchymal origin 

- composed of immature mesenchymal cells and spicules of dysplastic bone

- closely resembles the pattern of fibrous dysplasia and its variant ossifying fibroma 

 

Adamantinoma is considered by some to be a malignant variant of fibrous dysplasia

- resemblance of the mesenchymal component to fibrous dysplasia / ossifying fibroma

- the presence of the epithelial component makes adamantinoma a distinctly different entity

 

NHx

 

Intra-osseous, intra-cortical Stage 1A Osteosarcoma

 

Metastasis in 20% of cases

 

Management

 

Wide excision

 

Biopsy followed by wide resection

- chemo and radiotherapy ineffective

- need to address bone loss

- vascularised fibular graft / allograft / bone transport

 

Results

 

Qureshi et al JBJS Am 2000

- multicentred retrospective review of 70 cases

- average age 31, more common in males

- limb salvage attempted in 91% and successful in 84%

- up to 50% complication rate with limb reconstruction (fracture, non union)

- wide operative margins associated with lower recurrence rates

- 87% 10 year survival

 

 

 

 

 

 

Benign Fibrous Histiocytoma

Epidemiology

 

Older patients

- eipiphysis / diaphysis of long bones usually

 

Xray

 

Lytic lesion with sclerotic rim

 

Histology

 

Benign

- foam cells

- lipid filled cells

 

Treatment

 

Curette and bone graft

- chance of recurrence

 

 

Chondroblastoma

Definition

 

Rare cartilage tumour 

 

Epidemiology

 

1% of bone tumours / rare

- typically in adolescents

 

NHx

 

Usually benign

- but aggressive / frankly malignant behaviour reported

- locally aggressive

- can have pulmonary metastasis

 

Location

 

Arises in secondary ossification centre / epiphysis

- proximal tibia / knee

- proximal femur / hip

 

Develops < physis closes (unlike GCT)

 

Clinical

 

Usually painful

- may produce limitation of joint ROM

 

May produce altered epiphyseal growth in young children

 

X-ray

 

Eccentric epiphyseal 

- well-defined lucency

- thin sclerotic reactive rim

 

Proximal Tibial Chondroblastoma

 

Often internal stippled calcification

- popcorn or chicken wire calcification in 25%

- ± metaphyseal periosteal reaction

 

MRI

 

Rarely diagnostic

- many tumours will have areas of hemorrhage

- causes high signal intensity on T2

- i.e. GCT / ABC / chondroblastoma

 

Chondroblastoma Proximal Tibia MRI

 

Pathology

 

Histology

 

Stage 2 lesion typically / benign active

- active / intracapsular but with aggressive stroma

 

Chondroblastoma Histology

 

Sheets of chondroblasts and amorphous cartilage

- polygonal cells

- bluish cytoplasm

- cobblestone appearance of fine surrounding calcium like "chicken wire"

- occasional giant cells 

 

Atypical cartilage matrix

- stain +ve for S100 

- chondroid Matrix

 

DDx

  

Epiphyseal lesion in adults

- chondroblastoma

- GCT

- clear cell chondrosarcoma

- infection

- telangiectatic osteosarcoma

 

Management

 

Principles

- difficult to eradicate due to anatomic position without damaging joint or physis

- i.e. located in hip and knee close to joint surface

 

Options

 

1.  Currettage and bone graft

2.  Radiofrequency ablation

3.  Wide excision / usually necessitate allograft reconstruction or joint replacement

 

Intra - Lesional Curettage + Bone Graft

 

Chondroblastoma Intralesional Currettage and PMMA

 

Technique

- intra-articular exposure required

- meticulous debridement with burr

- local adjuvant treatment - Phenol / Liquid N2

- avoid damage to physis 

- allograft / autograft / PMMA

 

Problem

- may not be possible to prevent injury to joint due to location

 

Recurrence

 

More common in femur and foot/ankle

- should have CT chest to exclude pulmonary metastasis

- can be cured by second currettage

 

Results

 

Sallhan et al JBJS Am 2009

- retrospective review of 87 cases

- 32% recurrence by 24 months

- most likely with epiphyseal lesions

 

Ramappa et al JBJS Am 2000

- 73 patients treateed with 15% local recurrence

- 1 patient recurred 3 times

- one patient died of metastasis

- one patient was cured of metastasis by aggressive surgery

 

Radiofrequency ablation

 

Results

 

Rybak et al Radiology 2009

- 14 patients treated and available for follow up

- 12 had good relief of symptoms with no further treatment required

- 1 patient required repeat treatment

- 1 patient had collapse of chondral surface with residual tumour

 

Wide Resection

 

Indication

- usually requires resection / reconstruction of joint

- indicated for second recurrence

 

Pulmonary metastasis

- resect if possible

 

 

Chondromyxoid Fibroma

Definition

 

Benign neoplasm of cartilaginous origin composed primarily of myxoid cartilage

 

Previously thought to be Chondrosarcoma

 

Epidemiology

 

Very rare tumour

- young adults 10-30

- M:F 2:1

 

Location

 

Common upper tibia

- metaphysis of long bones

- lower limb predilection

 

Clinical

 

Tenderness

Local bulge

 

X-ray

 

Eccentrically placed metaphysis

- round or oval lucency

- well-defined sclerotic margin

- local expansion but cortex intact

- erodes / balloons the cortex

- characteristic buttress of periosteal new bone formation

 

Indistinguishable from an ABC

 

Pathology

 

Lobulated areas of spindle shaped stellate cells

- abundant myxoid / chondroid intercellular material

- multinucleated giant Cells

- merging of benign elements - hyaline cartilage / myxoid tissue / fibrous tissue

   

DDx

 

ABC 

Fibrous cortical defect

Fibrous Dysplasia

 

Management

 

Intra-lesional curettage & bone grafting

- recurrence common (40%)

- treat with wide resection

 

If Stage 3 lesion consider marginal or wide resection

 

 

Eosinophilic Granuloma

Definition

 

Langerhan's Cell Histiocytosis

- non-neoplastic disorder

- characterised by infiltration by histiocytic cells (Monocyte / macrophage lineage)

 

Group of granulomatous inflammatory processes of unknown aetiology

- involve the reticuloendothelial component of the bone marrow, parenchymal organs, and skin

 

Types 

 

E - H - L

 

1.  Eosinophilic Granuloma (70%)

- 5-20 years

- only manifestation is Osseous

- one or more lesions

 

2.  Hand-Schuller-Christian Disease (20%)

 

Think of as multiple EG's 

- more widespread granulomas

- systemic manifestation of EG 

 

Classically triad of

- diabetes insipidus  (parapituitary involvement)

- exopthalmos (orbital involvement)

- skull defects

 

Plus

- osseous lesions with mild to moderate visceral involvement

- lymphadenopathy

- hepatosplenomegaly both from EG

- skin lesions

- pulmonary disease

 

Less aggressive than LS

- 10% die

 

3.  Letterer-Siwe Disease (10%) 

- often infants < 1

- probably unrelated neoplastic condition

- rare disseminated disease of infants with fulminant course

- major visceral involvement: RES, pulmonary, anaemia

- death from hepatic failure

- less osseous involvement

 

Aetiology 

 

Unknown

 

Cell of origin is Langerhan's Cell

- ? immunoregulation disorder

- deficiency of Suppressor T-Cells

- uncontrolled macrophage proliferation 

 

Clinical 

 

Eosinophilic Granuloma (70%) 

- affects children age 4-7 years

- presentation variable & non specific

 

Back pain from vertebral lesion (most common presentation) 

 

Localised swelling (especially Skull)

 

Pain, limp & muscle wasting with pelvic or leg EG

- pathological fracture

 

Location 

 

Any bone may be affected

- skull / spine / femur / flat bones (ribs, pelvis)

 

Less common in long bones

- diaphyseal

- solitary lesion in 50%

- if multiple, < 3 lesions

 

Laboratory

 

Inconsistent & moderate elevation of ESR + anaemia

 

X-ray

 

1.  Vertebra Plana 

- compression of body

- vertebral body widened

- usually involves end plate rather than neural arch

- discs intact

 

DDx

- Ewings

- MM, Mets, Lymphoma, Leukaemia

- ABC

- infection

 

2.  Long Bones 

 

Diaphyseal osteolytic lesion

- thin sclerotic rim with endosteal scalloping

- cortical expansion with overlying periosteal reaction

- appearances vary according to stage of healing

 

DDx

- HALFEE

 

3.  Skull 

- most common site

- multiple punched out lucencies

- coalesce to give geographic skull

- typically bevelled edge appearance to lesion

 

MRI 

 

Lesion is low signal on T1 & high signal on T2 

- enhancing brightly with gadolinium (good discriminator)

 

DDx

 

Need to rule out HSCD or LS

- bone scan & skeletal survey

 

Pathology

 

Defect filled with lipid-laden histiocytes with eosinophilic cytoplasm

- plasma cells (blue with cartwheel nucleus)

- eosinophils (pink with bilobed nucleus)

- plasma cells with occasional eosinophils

 

Cytoplasm of cells contains specific Inclusion X bodies 

- same as Birbeck granules in Langerhans Cell 

- visible under EM

 

Positive staining for S100

 

NHx

 

Usually self-limiting

- fibroblasts obliterate histiocytes & inflammatory response

- tissue replaced by bone

 

Management

 

Vertebroplanar in infant

- self limiting

- will resolve

- no treatment required

 

Surgical indications

- symptomatic

- progressive

- neurological deficit

- at risk of pathological fracture

 

Options

 

1.  Intralesional steroid

 

Rimondi et al Skeletal Radiol 2009

- CT guided percutaneous intralesional methylprednisone

- success in 17/19 patients

- remaining two found to have systemic disease

 

Yasko et al JBJS Am

- 35 lesions

- resolution in all but one

- 97% success

 

2.  Curettage and bone grafting

 

HCSD & LSD

 

Systemic treament / chemotherapy

- radiotherapy for localised lesions

- alkylating agents + steroids

- poor results if recurrence within 1 year

 

 

Fibrous Cortical Defect

AKAFibrous Cortical Defect Femur Fracture

 

Non Ossifying Fibroma

 

Definition

 

A hamartomatous defect in the metaphyseal cortex of skeletally-immature adolescents

 

Fibrous cortical defect 

- < 2cm in diameter

 

Non ossifying fibromas 

- > 2cm

 

Aetiology

 

Localised defect in cortex of long bone

- failure of bone to form

 

Epidemiology

 

Most common skeletal lesion

- 35% of young children

- most common cause of pathological fracture in children

 

NHx

 

Self limiting

- usually ossify by early adulthood

- ? become bone islands

 

United Non Ossifying Fibroma

 

Location

 

Distal femur

Distal tibia

 

Clinical

 

Child

- incidental finding

- pathological fracture

 

X-ray

 

Non-Ossifying Fibroma 

- > 2 cm

- eccentric metaphyseal lesion

- sclerotic margin

- slight expansion of cortex

- usually < 1/3 diameter of bone

 

Fibrous Cortical Defect

- < 2cm

- small cortical lucency 

- sharply defined border

 

Pathology

 

Fibroblasts in whorling fibrous stroma

- multinucleated giant cells

- no bone formation

 

Management

 

Biopsy

 

Usually don't require biopsy

- biopsy if uncertain

 

Fibrous Cortical Defect

 

Management

 

Serial observation

- xray yearly

- 35% of children have them

 

Non Ossifying Fibroma

 

Indication for surgery

- large lesions

- > 1/2 diameter of bone

 

Management

- curettage & bone graft

 

Pathological fracture

 

Management

 

1.  Treat closed if possible

- fracture heals in normal length of time

- lesion may heal with fracture union

 

2.  If persists, curettage / graft

 

Fibrous Cortical Defect Femur FractureNon Ossified Fibroma ORIFNon Ossified Fibroma United

 

 

 

 

 

 

Fibrous Dysplasia

Definition

 

Developmental hamartoma in which areas of the skeleton fail to mature normally

- remain indefinitely as immature, poorly mineralized trabeculae

 

Pathology

 

Hamartoma of bone and fibrous tissue

 

McCune - Albright's Syndrome

 

Rare triad of

 

1.  Fibrous Dysplasia

 

2.  Cafe-au-Lait Spots

- irregular 'Coast of Maine'

- compare with regular outline of 'Coast of California' in NF

 

3.  Precocious puberty

 

Malignant transformation

 

Monostotic 0.4%

 

Polyostotic / Albright's 4%

- OS / FS / CS

 

Inheritance

 

Usually non genetic inheritance

 

Osteofibrous Dysplasia

 

Only Tibia

- precursor Adamantinoma

- more dense with trabecular pattern

- plump rimming osteoblasts

 

Types

 

1. Monostotic 85%

 

2. Polyostotic 15%

 

3. Associated with endocrinopathy

- Vit D Resistant Rickets

- Hyperthyroidism

- DM

- Acromegaly

- Cushing' s syndrome

 

Location

 

Any bone

 

Femur

- involved in 90% polyostotic

 

Tibia

 

Skull / maxilla / ribs

 

NHx

 

Usually diagnosed in children and adolescents

 

Remains relatively unchanged throughout life

- in keeping with developmental abnormality 

 

Clinical

 

Monostotic

- incidental finding

 

Fibrous Dysplasia Pelvis

 

Polyostotic

- usually present in childhood

- pain (indicates microfracture)

- pathological fracture

- limp

- deformity

 

X-ray

 

Intramedullary diaphyseal lesion

- 'ground glass appearance'

- tissue that is more lucent with a similar to the density of cancellous bone

- homogeneous with no visible trabecular pattern

 

Thinned, slightly bulged cortex

- ± endosteal scalloping

 

± Angular deformity at site of lesion

 

Coxa vara of proximal femur

- Shepherd's Crook deformity

- secondary LLD

 

Fibrous Dysplasia Hip0001Fibrous Dysplasia Hip0002

 

Sabre tibia

 

CT

 

Fibrous Dysplasia CT

 

Bone Scan

 

Skeletal Survey

- mono v polyostotic

- look for other lesions

 

MRI

 

Low T1 SI

Low - High T2 SI

 

Pathology

 

"Chinese letters"

- strands of osteoid & bone arising from fibrous stroma

- irregularly shaped bony trabeculae in fibrous stroma

 

Management

 

Principles

 

Basic rule is don't operate unless deformity

 

Any morcellised bone graft is resorbed

 

Guille et al JBJS Am 1998

- 100% resorption of bone graft with recurrence of lesion

- osteotomy and fixation with reconstruction nail mainstay of treatment

 

Medical Management

 

Bisphosphonates

- to relieve pain

 

Results

 

Chapuriat et al Bone 2004

- marked reduction in pain

- some resolution / filling in of lesions

 

Proximal femur

 

Aim 

- stabilise diaphysis

- prevent coxa vara

- try to wait until skeletal maturity

 

Management

 

1.  Valgising osteotomy

 

2.  Plate (immature) / Reconstruction Nail (mature)

 

Results

 

Yang et al Acta Orthop Trauma Surg 2010

- 14 cases with valus osteotomy / currettage / allograft and reconstruction nail

- good restoration of alignment with improvement in LLD 

- no recurrent fractures or progression of deformity

 

Sabre tibia

 

Management

 

Osteotomy + IM nail

 

THR

 

Beware large cysts

 

Fibrous Dysplasia Hip CT

 

Giant Cell Tumour

Definition

 

Benign lesion with a wide spectrum of behavior characterized by stromal cells and giant cells

 

Epidemiology

 

Common

- 20% of benign tumours

 

More common females

- F:M = 1.5:1

- most tumours M>F

 

Usually patient in 20's

- usually after skeletal maturity

- 3% < epiphyseal closure

 

Can behave in malignant fashion

 

Location

 

Epiphysis

 

Knee 50% 

- distal femur

- proximal tibia

 

Remainder

- distal radius

- sacrum

- vertebral bodies (anteriorly like EG compared with ABC/OO)

 

GCT Distal RadiusGCT Distal Radius CT

 

Clinical

 

Involved joint has

- dull ache

- effusion

- muscle atrophy

 

Pathological fracture common

 

X-ray

 

GCT Distal Femur Xray

 

Well-defined defect in epiphysis & metaphysis

- no sclerosis around lesion

- sub-articular with extension into subchondral bone

 

May extend into articular cartilage

- unique ability

 

Minimal periosteal reaction

 

± Cortical breach & soft tissue extension

 

DDx

 

Brown's tumour / hyperparathyroidism

 

MRI

 

Show cortical destruction & soft tissue extension

- soft tissue extension suggest stage 3 aggressive

 

GCT Distal Femur MRI0001GCT Distal Femur MRI0002

 

Bone Scan

 

Mono v polyostotic

 

Bloods

 

Ca++ / Se PO4

- rule out Brown's tumour

 

ESR 

- Osteomyelitis & EG

 

Pathology

 

Giant Cell Tumour Histology Nephron GNU Free Documentation License Version 1.2 httpwww.gnu.orgcopyleftfdl.html

 

Two Cell Types

A Multinucleated Giant Cells 

- similar to osteoclasts

- likely reactive

B.  Small Stromal Cells 

- ? the actual tumour 

- probably osteoblast derivatives

 

Background of fibrous tissue

- normal mitoses usually seen

- areas of spontaneous necrosis (rare for benign tumours)

- thin cortical shell

 

Campanacci Stagin

 

Stage I Latent (15%)

 

Sclerotic Rim

- asymptomatic

- inactive on bone scan

- histologically benign

 

Stage II Active (70%)

 

Expanded cortex but no breakthrough

- symptomatic

- often have pathological fracture

- active on bone scan

- histologically benign stromal cells

 

Stage III Aggressive (15%)

 

Rapidly growing mass

- cortical perforation with ST mass

- symptomatic

- extensive activity on bone scan

- histologically benign

 

Malignant

- rare form

- sarcomatous lesion contiguous with benign GCT 

 

Prognosis

 

Previously said 10% metastasize

- many of these would now be called MFH

- for it truly to be giant cell have to see typical appearance of GCT in metastasis

 

Primary malignant GCT better prognosis than malignant change in recurrence

 

DDx

 

ABC / UBC

Chondroblastoma

Clear cell sarcoma

Telangiectatic Osteosarcoma

Synovial cyst of OA / Geode

PVNS 

OM (brodies abscess)

 

Because there are 2 malignant tumours which can mimic

- all need careful staging and biopsy

 

Management

 

Staging

 

Biopsy usually performed

 

Options

 

1.  Currettage + bone graft / PMMA
2.  Wide excision + allograft / arthroplasty

3.  Adjuvant treatment

 

Grade I & II

 

Management

 

Currettage and PMMA

- extended curette with high speed burr

- saucerisation 

- bone graft under subchondral bone

- adjuvant PMMA (works by thermal necrosis)

 

GCT Distal Femur PMMA

 

Results

 

Blackley et al JBJS Am 1999

- treatment of 59 patients with high speed burr and autograft / allograft

- 12% local recurrence

 

Becker et al JBJS Am 2008

- demonstrated reduced local recurrence with the use of PMMA

 

Bauer et al JBJS Br 2006

- treatment of recurrences with repeat currettage and PMMA

- 13/15 successful after one treatment, remainder after 2

 

Grade III & Recurrence

 

Management

 

Wide resection & osteochondral allograft / arthroplasty + adjuvant DXRT

 

Indications

- extensive soft tissue tumour

- extensive cortical destruction / pathological fracture

- joint destruction

 

Results

 

Bell et al J Arthroplasty 1994

- fresh osteochondral allograft for distal femur in 16 patients

- 3 revisions and 1 late infection

- 8/13 assessed were good or excellent

 

Unresectable

 

DXRT

- i.e. sacral and pelvic GCT

 

Bisphosphonates

 

Theory

 

GCT rich in osteoclast derived cells

 

Results

 

Balke et al BMC 2010

- use of bisphosphonates in aggressive primary / recurrent / metastatic GCT

- no increase in size in inoperable tumours

- no recurrences in tumours that had repeatedly recurred

- lung metastasis did not increase in size or number

 

Recurrence rates

 

Enneking

- grade 1 = negligible recurrence

- grade 2 = 20%

- grade 3 = 70%

- grade 3 + adjuvant = 20%

 

Metastases

 

Lung metastases occur in 2%

- lesions slowly progress ie benign in nature

- usually treat with surgical resection

- consider GCT benign if pulmonary metatasis histologically benign

- regular CXR in patients with GCT

 

 

 

 

Haemangioma

Definition

 

Hamartomatous proliferation of vascular tissue

 

Epidemiology

 

Commonest tumours in infancy & childhood 

- usually superficial

 

Types

 

Capillary

- majority

- small nodules of capillary sized vessels lined by flattened endothelium

- nodules clumped in lobular pattern

 

Cavernous 

- less common

- usually larger & involve deeper structures

 

Associations

 

1.  Klippel Trenaunay Weber Syndrome 

- hemihypertrophy with underlying venous malformations

- secondary to increased angiogenesis

- UL, LL or both affected

- usually unilateral

 

2.  Maffucci Syndrome

 

3.  Sturge-Weber

- rare congenital / not hereditary

- often facial capillary malformation

- more extensive hemangiomata

- mental retardation / seizures / hemiparesis  

- hemiatrophy

 

Site

 

Cutaneous

Subcutaneous

Intramuscular

Intra-osseous

 

Clinical

 

Ache

Limb heaviness

Lesions in the skin - distended bluish discoloration 

Deeper intramuscular lesions present as a tender mass

 

X-ray

 

Soft-tissue lesions

- same radiodensity of muscle

 

Often small calcified nodules / phleboliths

- circular pattern with a radiolucent center (due to recanalization) 

- same as those seen in the pelvic veins of multiparous females

 

MRI

 

Exceedingly bright signal 

- due to the high fluid content of the lesion 

 

CT

 

Polka dot appearance due to section through the vessels

 

These lesions often penetrate the bone and have a large soft tissue component

 

Management

 

As pain / disability demands

- often observation

 

Soft tissue Hemangioma

 

Hemangioma Soft TissueHemangioma Embolisation

 

Non-operative

- stockings

- simple analgesia

 

Operative 

- resection

- embolization

 

Beware rare cases of malignant change

 

Intraosseous Hemangioma

 

Epidemiology

- F:M = 2:1

- incidence increases with age

- 0.8% of 1° bone tumours

- commonest sites are spine (especially thoracic) & skull

 

X-ray

 

Characteristic finding is the coarsened vertical trabeculae

 

Spine 

- honeycomb or corduroy cloth appearance

- in spine this finding is usually sufficient for the diagnosis

 

Skull 

- spoke-wheel configuration

 

CT

 

Characteristic finding is multiple dots "polka dots"

 

MRI 

 

Usually bright on T1 & T2 images because of fat content

- areas of trabecular thickening will have low signal intensity

 

Hemangioma Spine

 

 

 

Osteofibrous Dysplasia

Definition

 

Congenital hamartomatous lesion

- occurs almost exclusively in the tibia or mandible

- striking resemblance to fibrous dysplasia

- thought by many to be a variant of that condition

 

Location

 

Anterior cortex of tibial diaphysis

Mandible

 

Clinical

 

Young child

 

Anterior bow or mass in tibia

 

Pathological fracture common

 

X-ray

 

Multiple small radiolucent lesions

 

Rim of reactive bone

 

DDx

 

Adamantinoma

Fibrous Dysplasia

EG

Ewing's

Periosteal OS

 

Management

 

Issue

 

Risk of adamantinoma in lesion

- recommended excision of all lesions

 

Currettage alone

- 100% recurrence rate

 

Results

 

Lee et al JBJS Br 2000 

- review of 16 patients with osteofibrous dysplasia tibia

- 6 treated initially with currettage / all recurred

- treated with segmental excision and management of bone defect

- some small lesions

- others requiring fibular graft or bone transport

- 3 confirmed cases of adamantinoma

- no recurrences

- recommend excision in all cases

 

 

 

Periosteal Chondroma

Definition

 

Metaphyseal Enchondroma

 

Site

 

Arise from the metaphyseal cortex of long bones

- most common in the proximal humerus

 

Histology

 

Difficult to DDx from Chondrosarcoma

 

Masses of cartilage nestling in a shallow crater in the periphery of the cortex

 

NHx

 

Don't ossify

- remain as immature cartilage

 

No malignant potential

- Don't transform into CS

 

DDx

 

Juxta-cortical chondrosarcoma

Periosteal osteosarcoma

 

Unicameral Bone Cyst

AKAUnicameral bone cyst femur

 

Simple Bone Cyst

 

Definition

 

A simple bone cyst is a solitary cavity containing clear fluid

- originating in the metaphysis of growing children

- adjacent to the metaphyseal aspect of the growth plate.

 

Aetiology

 

Unknown pathological origin

- likely secondary to venous obstruction / hypertension

- probably not neoplastic

- occurs during growth

 

Epidemiology

 

Children

 

M 2:1

 

Location

 

Proximal metaphysis 

- humerus 67% 

- femur 15%

 

Often immediately below physis

- metaphyseal side

 

Can occur in os calcis

 

Types

 

Active

- adjacent to physis

 

Latent

- separated from physis by normal bone

 

Clinical 

 

Present with pain caused by pathological fracture

- commonest presentation 75%

 

X-ray

 

UBC HumerusUBC Humerus 2

 

Metaphyseal near physis

- well-defined lucency 

- thin sclerotic rim

- usually central

- thinned cortex with slight expansion

- thin internal septa

- can be multi-loculated

 

Fallen-Leaf sign 

- with pathological fracture

- "Classic" sign

- pathognomonic because indicates that the lesion has no matrix & is fluid filled 

 

DDx ABC

 

ABC

- eccentric (v central)

- width > physis

- can be very difficult to tell

 

Pathology

 

Pressure

- they have an arteriolar pressure curve

- cyst pressure is higher than venous pressure

 

Fluids

- contain high levels of prostaglandins

- contain high levels of alkaline phosphatase

 

Gross

 

Thin cyst lining with fine septae

- contains clear fluid compared with ABC

 

Histology

 

Thin fibrous layer of CT 

- cells resembles synovial cells

- few multinucleated giant cells

 

NHx

 

Tend to become latent

- resolve in adulthood

- may resolve post fracture

 

Management

 

Issue

 

Will eventually heal, but tend to fracture up to 4 times on average

 

1.  Humerus

- fractures will heal in sling

- must then avoid non contact sports

- difficult to tell child not to play sports for many years

 

2.  Femur

- want to prevent fracture

- avoid morbidity / deformity

 

Options

 

Observe

Inject HCLA

Inject bone marrow aspirate

Currettage and bone graft

Cyst drainage

- cannulated screws

- IM rods

ORIF

 

Observation

 

Inactive & small

 

Aspiration and injection HCLA

 

Technique

 

Aspirate initially

- if aspirate blood / treat as ABC / biopsy

- if aspirate fluid / simple cyst

 

Inject contrast

- ensure not loculated

- if it is, need to inject all parts of cyst

 

Inject methylprednisolone

- steroid blocks PGE

- methylprednisolone 50 - 200mg

- second needle as vent

 

Results

 

Rud et al Orthopaedics 1991

- 11 UBC treated with injection of methyprednisolone

- 2 required second treatment

- 5 cysts resolved completely whilst 6 resolved sufficiently that fracture was no longer a risk

 

Bone marrow injection

 

Technique

 

GA / Aspirate from bone marrow

- inject into cyst under II

 

Results

 

Rougraff et al JBJS Am 2002

- 25 cases treated with percutaneous bone marrow aspirate

- combined with demineralised bone matrix

- 5 recurrences

 

Wright et al JBJS Am 2008

- RCT of bone marrow aspirate v HCLA in 77 patients followed for 2 years

- 42% in the methylpredisolone group healed

- 23% in the bone marrow group healed

 

Curettage + Bone Graft

 

UBC Humerus DrillingUBC Humerus Curettage

 

Results

 

Hunt Orthopedics etal 2009

- 21 proximal humeral cysts

- 75% union rate

 

Cyst drainage

 

Concept

- venous hypertension cause of cyst

- if allow cyst to drain, will heal

 

Options

- cannulated screw into lesion

- TENS nails humerus

- IMN femur

 

Results

 

Linhart et al Orthopedics and Traumatology

- 21 proximal humeral cysts

- distal to proximal flexible nails

- 95% union rate

 

Hou et al JBJS Am 2010

- humeral cysts

- 11/12 healing with currettage / synthetic bone graft / cannulated screw

 

Specific Regions

 

1.  Humeral Unicameral Bone Cysts

 

Treat fractures non operatively in sling initially

- need treatment if debilitating

 

Options

1.  Non operative / avoid contact sports and wait

2.  Injection HCLA

- minimally invasive, perform in OT

3.  Percutaneous TENS nails

 

2.  Proximal Femur Unicameral Bone cysts

 

Pathological fracture

- treat in traction / spica if minimally displaced or very young

- otherwise paediatric sliding hip screw

- reconstruction nail if > 15 years

 

Non fractured but high risk

- trial injection

- paediatric hip screw if < 15 with bone grafting

- IMN if > 15

 

Unicameral Bone CystUnicameral Bone Cyst IM Nail

 

                   

 

 

 

Sclerotic Lesions

Bone Infarct

Epidemiologybone Infarct Knee

 

In caisson workers / divers

Sickle cell anemia

Long term steroid

 

Aetiology

 

May sometimes be a degenerating lipoma of bone

 

DDx

 

Chondroblastoma / Chondrosarcoma

- if in metaphyseal region

 

Enchondroma

 

Bone island

 

Bone Scan

 

No increased uptake

 

Histology

 

Mineralisation of necrotic marrow elements

 

Prognosis

 

MFH may arise from long standing bone infarcts

 

 

Enchondroma

 

DefinitionEnchondroma Hip

 

Benign intramedullary cartilage lesion

 

Aetiology

 

Enchondroma are presumed to be remnants of hyaline cartilage

- derived from the epiphyseal growth mechanism that failed to undergo enchondral ossification

 

Epidemiology

 

10% of benign bone tumours

 

Young adults

 

Stop growing in adults and calcify

 

Malignant transformation 

 

Rare

- enchondroma in hands and feet always benign

- benign looking enchondroma located centrally may be malignant

 

Age 

- in general not malignant prior to maturity

 

Bone scan not helpful

 

Histology not helpful

 

Location

 

Intramedullary

 

Start near physis (metaphyseal) but may become diaphyseal

 

Involves any bone formed by endochondral ossification

- especially tubular bones of hands & feet

- 50% in hands, especially phalanges

- 10% in feet

- also common femur, humerus & ribs

 

Can have periosteal chondroma

- surface long bones

- calcified matrix

- well demarcated cortical defect

 

Clinical

 

Usually incidental finding

- may be patholological finding

 

X-ray

 

Enchondroma Distal Femur0001Enchondroma Distal Femur0002

 

Intralesional calcification in adults

- especially in long bones

- punctate, stippled calcification and broken rings

 

Shoulder EnchondromaShoulder Enchondroma CT

 

No periosteal reaction

 

Suspicious Lesion (5)

 

Chondrosarcoma

 

1. X-ray appearance

- scalloping (endosteal erosion)

- periosteal reaction

- fluffy calcification

 

2.  Size > 6-10 cm rarely benign

 

EnchondromaEnchondroma

 

3.  Peripheral vs central 

- central pelvis / shoulder girdle more concerning

 

4.  Age - malignancy rare <20

 

5.  Solitary vs Olliers

- benign more cellular in Olliers

 

Bone Scan

 

Usually increased uptake

 

MRI

 

MRI Enchondroma0001MRI Enchondroma0002

 

Pathology

 

Composed of masses of hyaline cartilage without characteristic architecture

- typically bland cartilage

- no pleomorphism / anaplasia / hyperchromasia

- hand lesions tend to look more hypercellular & pleomorphic

 

Enchondroma Nephron GNU Free Documentation License Version 1.3

 

Can be very difficult to distinguish between low grade chondrosarcoma and enchondroma

 

DDx

 

Long Bone with Intralesional Calcification

1.  Enchondroma

2.  Bone infarct 

3.  Chondrosarcoma

 

Phalanx

- epidermoid inclusion cyst

- glomus tumour

 

Staging

 

Plain radiograph

- biopsy usually not required

 

Management

 

Options

 

1.  Observation

 

Biopsy

- enlarging

- becomes painful

 

2.  Prophylactic Resection

 

Doesn't require prophylactic resection because

 

A.  Malignant transformation very rare <1%

- usually in pelvic or shoulder girdle

 

B.  Transform to chondrosarcomas

- low-grade, slowly growing and painful

 

3.  Hand fracture through enchondroma

 

Allow to heal non operatively if possible

Curettage and bone graft once united

 

Enostosis

AKA

 

Bone island

 

Definition

 

Hamartomatous lesion 

- island of mature cortical bone found in the midst of normal cancellous bone 

 

Epidemiology

 

>10

 

M=F

 

Clinical

 

Asymptomatic x-ray finding (usually in adolescents)

 

X-ray

 

 

Shoulder Bone Island

 

Sharply-circumscribed cortical densities

- usually round or oval in shape with smooth, regular borders

- sharp / narrow zone of transition from lesion to cancellous bone 

- no evident reaction to the process

 

Range in size from a few mm to several cm

- more commonly less than 1 cm in diameter

 

CT 

 

Even cortical texture

 

Management

 

Observation

 

Osteopoikilosis 

 

Multiple bone islands

- sclerosing skeletal dysplasia

- AD inheritance

- hips / pelvis / sacrum / femur / humerus

- characteristically periarticular

- lesions asymptomatic and cold on bone scan

- malignant transformation extremely rare

 

 

 

 

 

Melorheostosis

Epidemiology

 

Rare, non-hereditary lesion

- 1: 1 000 000

 

M = F

 

Apparent in early childhood and even in the first few days of life

 

About 50% of persons affected will develop the symptoms by 20 years of age

 

Aetiology

 

Unknown

 

Theory 

- lesion arises from an abnormality of the sensory nerve of the affected sclerotome

- sclerotome is a zone of the skeleton supplied by an individual spinal sensory nerve

- represents a basic unit of vertebral embryonic development.

 

Clinical

 

Pain, joint stiffness, and progressive deformity

- mainly the bones of the extremities and pelvis

 

LLD, deformity

 

Joint contractures

- secondary to extraosseous bone formation

 

Can cause spinal stenosis

 

Can have extensive ST masses, which can ossify

 

X-ray

 

Sclerotic lesions of bones 

- undulating cortical hyperostosis

- look like wax dripping down the side of a candle

 

Bone Scan

 

Increase uptake

 

MRI

 

Heterogenous

- mix of osseous, fibrous, adipose, cartilage

 

Biopsy

 

Variable degree of marrow fibrosis

- with markedly irregular bone with mixed areas of lamellar and woven bone

- mixture of osteocartilagenous, fibrovascular, and adipose tissue is seen in the soft tissue masses

 

NHx

 

The clinical course is slowly progressive

 

Severe symptoms may require treatment by sympathectomy or even amputation

 

Isolated cases of malignancy have been reported in association with melorheostosis

- one osteosarcoma and one malignant fibrous histiocytoma

 

 

 

 

Multiple Enchondromas

Multiple enchondroma occur in two circumstances

 

1. Ollier's

-  distributed symmetrically in an extremity

 

2. Maffucci's syndrome

- randomly distributed throughout the skeleton

- in association with hemangiomas

 

Ollier's Disease

 

Site

 

Enchondromas symmetrically distributed through an extremity

 

Usually unilateral and monostotic

 

Epiphyseal, metaphyseal or diaphyseal

 

Inheritance

 

Not heritable / embryonal disorder

 

Problems

 

1.  Often associated deformation of growth

- LLD

- bowing wrist

- bowing elbow

 

2.  Malignant transformation

- 25% at 40 years

 

Maffucci's Syndrome

 

Clinical Features

 

Multiple enchondromas 

- randomly distributed

- associated with hemangiomas

 

Problems

 

1.  100% risk of malignant transformation 

- usually long latent phase

- 30 - 50 years of age

 

2.  Associated with other tumours

- visceral carcinoma

 

3.  Cutaneous hemangiomata

- bring diagnosis to attention

 

4.  Skeletal deformity

- short tubular bones hands & feet

- long bones of UL / LL

- one side of body usually more severe

- palpable mass

- LLD

- bowing of forearms

- varus / valgus of legs

 

Management

 

Osteotomy through lesion to correct angulation

 

Epiphyseodesis or limb lengthening

 

Curettage & grafting of large lesions interfering with function

 

Need lifetime vigilance for tumour transformation

 

Multiple Hereditary Exostosis

AKA

 

Diaphyseal Aclasis / Multiple Osteochondromas

 

Definition

 

Heritable skeletal dysplasia

 

Epidemiology

 

AD with variable penetrance (96%)

 

Malignant Transformation

 

Incidence of malignant transformation much higher 

- 10% overall

- 1 % / year

 

Chondrosarcoma (CS) > Osteosarcoma (OS)

 

Secondary CS has better prognosis than primary CS prognosis

 

Danger areas / central

- pelvis

- scapula

- proximal humerus

- proximal femur

- spine

 

Clinical

 

Mildly short stature

 

Nerve compressions

 

Upper Limb

 

Scapular involvement (winging)

 

Forearm involvement

- ulnar deviation of wrist

- loss of pronation / supination

 

Lower Limb

 

LLD

Valgus knees

Valgus ankle

CPN compression

 

Multiple OsteochondromasMultiple Osteochondromas

 

X-ray

 

1.  Coxa Valga

- neck short & broad

 

Hip OsteochondromaOsteochondromas Hip

 

2.  Genu valgum

 

Osteochondroma KneeOsteochondroma Knee Lateral

 

3.  Ankle valgus

- fibular shortening with valgus distal tibia

- wedge-shaped distal tibial epiphysis

- leads to valgus talar tilt in abnormal mortise

 

Osteochondroma Ankle

 

4.  Forearm 

- ulnar shortening with radial bowing

- ulnar deviation of wrist

- radial head dislocation

 

Osteochondroma ElbowOsteochondromas Forearm 1Osteochondromas Forearm 2

 

Osteochondromas WristOsteochondromas Wrist Lateral

 

Histology

 

Exostoses tend to be more disorganised with bosselated cartilage cap

 

Management

 

Principles

 

Excision of symptomatic osteochondromas

Removal of suspicious lesions

 

Sites

 

Forearm

 

Most disability 

- maybe little functional loss

- pronation / supination decreases with age

 

No evidence that OT will improve function

- distal radial osteotomy / hemiepiphyseodesis

- lengthening of ulna

- excision of local osteochondromas

 

Ankle

 

Chin et al JBJS Am 2000

- demonstrated that early removal in full of osteochondroma

- allowed remodelling of deformity

 

1.  Guided growth

- slow growth medially / screw or 8 plate

- allows lateral fibular growth to correct valgus

 

2.  Supramalleolar osteotomy / Ilizarov correction

- deformity correction

 

Knee

 

High incidence of valgus tibial deformity

Case reports of popliteal pseudoaneurysm

 

Osteochondromas Valgus KneeOsteochondromas Knee Osteotomy APOsteochondromas Knee Osteotomy 2

 

 

 

Nora's lesion

 

It was described in 1983 by Dr. Nora, and is sometimes called Nora's disease or Nora's lesion

 

Definition

 

Bizarre parosteal osteochondromatous proliferation 

 

Epidemiology

 

Rare lesion 

- occurs most commonly in the hands and feet

 

Adults in their 20's and 30's

 

Males = Females

 

Site

 

Most common in the hands 

- followed by the feet

- long bones (commonly of the upper extremity)

- skull, jaw

 

Hands

- proximal and middle phalanges

- metacarpals

 

NHx

 

Grows rapidly

- aggressive features on imaging 

 

Clinical

 

Mildly painful mass 

- seems to increase in size over many weeks or a few months

- usually no history of trauma

 

X-ray

 

Bony mass

- well defined margins 

- seen to be applied to the surface of the bone

- it may project into the soft tissues

- lacks the characteristic orientation away from the nearby physis that is seen in osteochondromas. 

 

Wide base

- may appear pedunculated

 

Matrix

- mature, trabeculated bone

 

CT

 

Osteochondromas

- cortex and medullary cavity of the bone is continuous with the cortex and medullary cavity of the lesion

 

BPOP / Nora's

- cortex and medulla not contigous with cortex

- no cartilage cap

 

MRI

 

Typical tumour picture

- high SI on T2

- low SI on T1

 

No cartilage cap

 

DDx

 

Parosteal / periosteal OS

 

Pathology

 

Gross 

- nodular surface covered with glistening cartilage.  

- bone in the lesion has a distinct blue tint 

- The cut surface of the lesion bleeds freely

 

Histology

 

Very cellular cartilage

- proliferation of bizarre fibroblasts

- disorganized bone with spindle shaped fibroblasts in the intertrabecular spaces

 

Confusion with 

- chondrosarcoma

- fibrosarcoma

- low grade parosteal osteosarcoma

- conventional osteosarcoma.  

 

NHx

 

Lesion is benign 

 

Management

 

Wide excision

- limits local recurrence

 

Recurrence

- may recur locally in as many as 50% of cases

- seen from 2 months to 2 years after surgery

 

 

 

 

Osteoblastoma

Epidemiology

 

Uncommon

 

< 1% Primary bone tumour

 

Young boys

- second decade

 

Location

 

Similar to OO

 

Spine 30%

- especially posterior elements

 

Long bones 35%

 

Clinical

 

Back or limb pain

- pain less severe than OO

- not dramatically relieved by aspirin

 

Limp

 

Scoliosis

 

X-ray

 

Spine

- difficult to see

- irregular cortex

- sclerotic or loss of pedicle

- enlargement of spinous process

 

Long Bone

- less diaphyseal occurrence than OO

- more common meta-diaphyseal

- large faintly radiolucent lesion

- thin reactive rim

- may be expansile

 

CT 

 

Demonstrates spinal lesion well

- bone expansion

- intralesional stippled ossification

 

Osteoblastoma CT 1Osteoblastoma CT 2

 

Bone Scan

 

Uptake +++

 

DDx

 

Osteoid osteoma

- < 2 cm

 

Pathology

 

> 2cm diameter

- less reactive rim

- otherwise identical to OO

- osteoid

 

Can be difficult to differentiate from OS 

- may also see changes of ABC

 

NHx

 

On rare occasion have acted aggressively

- bone destruction & soft tissue extension

- however don't metastasise

 

Management

 

Options

 

1.  Excision with wide margin

- preferred

 

2.  Extended curettage

- indicated in spine

- recurrence not uncommon, & difficult to treat

 

3.  Radiofrequency ablation

 

 

Osteochondroma

Definition

Osteochondroma Hip

 

Outgrowth of benign cartilage from bone

 

Epidemiology

 

50% of benign bone tumours

- single lesion in 90% 

 

Aetiology

 

1.  Multiple

Tumour suppressor gene

- family of tumour suppressor genes involved

- have been identified in chondrosarcomas

- 2 hit model of tumourigenesis

 

Both alleles must be mutated for an osteochondroma to form

- if inherit an abnormal allele need other allele to undergo mutation to form osteochondroma

 

 

2.  Single

? Secondary to injury of growth plate

- defect in Perichondral Ring La Croix

- results from herniation & separation of fragment of physis through the periosteal bone cuff 

 

NHx

 

Grows by endochondral ossification of enlarging cartilage cap

- stops at maturity

 

Malignant Transformation

 

Low-grade Chondrosarcoma

- isolated lesion < 1% 

- more common with central lesions

 

Suspicious features (6)

1.  Growth after maturity

2.  Hot bone scan (can be from overlying bursa)

3.  Increased thickness of cartilage cap on CT

- > 1-3 cm (Enneking) 

4.  Pain

5.  Pathological fracture

6.  Disappearance of calcification

 

Enneking

- when the rim of cartilage in an adult exceeds 25 millimeters, it is highly suggestive of malignant transformation

 

Location

 

Any bone formed by endochondral ossification

Arises from cortex of long bone adjacent to physis

 

Most common 

- around knee 

- proximal humerus

 

Clinical

 

Commonly noticed during adolescent growth spurt

 

Symptoms of mass lesion

- pain & tenderness

- decreaed ROM

- compression of NV structure

 

X-ray

 

Femoral Osteochondroma

 

Protuberant bony lesion

- arising adjacent to physis

- directed away from joint

- cortical bone continuous

- marrow space continuous 

- cartilage cap may be calcified

 

Types

1. Pedunculated / exostosis

2. Sessile

 

CT

 

Cortex and medullary cavity of normal bone contiguous with osteochondroma

 

MRI

 

See cartilage cap

- iso-intense with hyaline cartilage

 

Pathology

 

Gross

- looks like cauliflower

- surface covered with irregular cartilage

- cartilage usually 3-5 mm adults

- 5 - 10 mm children

- bone has cortex & medulla 

 

Histology

- cap resembles disorganised physis

- irregular shaped underlying trabecular bone

- may contain calcified cartilage matrix

 

DDx 

 

Juxtacortical OS / CS

Periosteal Chondroma

Osteoma

 

Management

 

Surgical Indications

 

1. Excise painful mass

2. Tendon / NV impingement

3. Restore joint motion

4. Correct deformity

5. Biopsy suspicious lesions

6. Central / pelvis / scapula 

- due to higher malignant transformation rate

 

Osteochondroma irritating Pes anserinus

 

Osteochondroma Cartilage CapOsteochondroma Excised

 

 

 

Osteoid Osteoma

Definition

 

Benign, bone-forming neoplasm

- characterized by a small nidus of neoplastic tissue

- surrounded by a wide zone of mature, reactive bone

 

Epidemiology

 

10% of benign bone tumours

Age 5-25

M:F 2:1

 

Aetiology

 

Unknown

- thought may be glomus tumour of bone

 

Pain secondary to prostaglandin production

 

Site

 

Intra-cortical position usually

 

60% femur, tibia

- usually at end of diaphysis 

- cancellous or cortical 

 

Posterior elements spine

 

Clinical

 

Characteristic pain

- intense, unrelenting ~ toothache

- night pain

 

Relief by aspirin / salicylates

- dramatic

- often within 30 minutes of one dose

 

May be worsened by ETOH

 

Scoliosis

 

Joint effusion if juxta-articular

 

NHx

 

Gradual resolution with time

 

X-ray

 

A.  Medullary OO

 

Four Diagnostic Features / 50% show all 4

1.  Sharply round or ovoid

2.  < 1cm

3.  Homogenously dense centre

4. ~ 1mm peripheral radiolucent zone

 

B.  Intra-cortical OO

- area of dense bone

- often fusiform-shaped

- central nidus usually not seen

- mimics stress fracture

 

Bone Scan / SPECT

 

Uptake +++

 

Useful to locate lesion especially in spine

 

CT 

 

Thin slice CT best investigation

- lucent nidus

- surrounding dense bone

 

Osteoid Osteoma CT

 

MRI

 

Pathology

 

Gross

 

Lesion is nidus

- < 1 cm diameter

- cherry red & granular

- dense reactive bone peripherally

 

Histology

 

Osteoid Osteoma Histology Nephron GNU Free Documentation License Version 1.2 httpwww.gnu.org/copyleft/fdl.html

 

Immature trabeculae enveloped by prominent osteoblasts / clasts

 

Lucent zone

- surrounding zone of hyperaemic fibrous tissue

- thin lacelike woven bone seams

- AKA osteoid seams 

- haphazard

- numerous vascular channels & rich nerve fibres 

- osteoblasts & giant cells surround

- no chondroid elements

 

No haemopoietic elements in vascular channels

 

Osteoid surround by vascular fibrous stroma

 

DDx

 

Cortical

- infection

- stress stress fracture

- parosteal OS

- osteoblastoma

 

Medullary

- VINDICATE pneumonic

 

Management

 

Non-operative

 

NHx

 

Can resolve

- ? spontaneously heals 

- takes a long time

- NSAID for pain relief

- doesn't progress to cancer

 

Operative

 

Goal is to remove the nidus

 

1.  En Bloc Excision

 

Gold standard

- ensures all of lesion excised

- weakens bone

- risk of fracture especially with lesion in femur

- need bone graft & protection

- send for intra-operative fresh frozen section to ensure have excised OO

 

2.   "Burr Down" Technique

 

Technique

- intraoperative CT guidance

- direct incision over lesion

- shave cortex off with high speed burr to reactive bone 

- scoop nidus out once hit hypervascular zone & sent for FFS

- burr 2mm zone out

- can leave strong reactive bone behind

 

3.  Percutaneous Guided Reaming

 

CT guided in xray suite

- doesn't produce tissue for histology

 

4.  Radiofrequency Ablation

 

Osteoid Osteoma Radiofrequency Ablation0001Osteoid Osteoma Radiofrequency Ablation0003

 

Technique

- GA

- introduce electrode under CT

- can take tissue for histology

- radiofrequency

- increase temperature for 6 mins to 90o

 

Contraindication

- spine

- risk thermal injury to spinal cord / nerve roots

 

Results

 

Rosenthal et al JBJS Am 1998

- equal rates recurrence (9%)

- no complications

- increased patient satisfaction

- drastically reduced in patient stay

 

 

 

Osteoma

Definition

 

Benign, hamartomatous bone-forming lesion arising from the surface of the affected bone

 

Aetiology

 

Excrescence of dense bone which arises from the surface of bones formed by intra-membranous ossification

 

Epidemiology

 

Age 25-50

 

M=F

 

Site

 

Skull or mandible

- classically

 

Shafts of long bones

- often see posterior femur

- similar location to parosteal OS

 

"flat bones and tibial diaphysis"

 

Pathology

 

Gross

- dome-like outcropping

- dense bone

- covered by a capsule confluent with the periosteum

 

Histology

- heavy trabecular bone

- matures into dense cortical bone 

- over-maturation 

- many small haversian canals

- some canals are obliterated 

 

DDx

 

Parosteal osteosarcoma

Exostosis

 

Prognosis

 

Active stage 2 lesion 

- never goes to 3 or 1

 

Association

 

Gardner's Syndrome

 

Management

 

Intracapsular or marginal excision 

- removing the lesion from the surface of the bone

- negligible risk of recurrence

- wide en bloc excision not necessary