Benign Bone Tumours

Classification (Benign lesions)

Nearly all occur in adolescents
Lesions usually stop growing when bone growth is complete
Classification
Stage 1
Latent G0, T0, M0
Negligible recurrence with intra capsular excision
Stage 2
Active G0, T0, M0
Significant recurrence rate after intra capsular excision
Marginal excision OK as tumour still intra capsular
Stage 3
Aggressive G0, T1-2, M0-1
Wide excision required (outside reactive zone) in order to limit recurrence risk
Recurrence rates after various margins of excision of benign tumours

Stage

1
 2
 3
Intra capsular (curettage)
 0
 30%
 50%
Marginal (excision)
 0
 0
 50%
Wide (excision)
0
 0
 10%
Radical (excision)
 0
 0
 0


Osteoma

Rare sessile ivory hard bone usually on the surface of the skull

Incidence

Male : Female 2:1
Peak age 30 - 50 years

Osteoid osteoma

Small, benign, solitary painful lesion of bone seen mainly in children and adolescents

Aetiology

Unknown

Incidence

Accounts for 10% of benign bone tumours
Male : Female 2:1
Peak age 5 - 25 years (85% in this range)
Rare over 40 years
Only occurs in bones formed by enchondral ossification

Clinically

Pain ® presentation
Pain often worse at night and relieved by aspirin
10% occur in the spine and may ® scoliosis
Other sites may ® joint effusion, LLD, synovitis
Runs a self limiting course but usually ® surgery for pain relief
Pain usually decreases as the lesion matures lasting 18 - 30 months
Lesion healed by 3 - 7 years

X-Rays

Hot spot on bone scan
Lytic nidus surrounded by sclerotic bone
Centre of nidus may be calcified
CT or tomograms ® diagnosis

Pathology

Maze of osteoid tissue with trabeculae of newly formed, poorly mineralised bone in a vascular connective tissue network encased in dense reactive bone
Contains fibroblasts, osteoblasts and osteoclasts, no marrow element
May have a calcified centre in the nidus
Nidus usually less than 1cm diameter, most less than 0.5cm

Treatment

Observe and analgesia
En bloc excision ® no recurrence (need only intact rim of reactive bone around the nidus to ensure complete excision
Beware the dumbbell nidus

Localisation of the lesion

4mg tetracycline per kg qid 1-2 days pre operatively ® specimen excised under UV light
Tc99 2 - 3 hours before surgery and ® geiger counter to identify nidus
X-Ray excised tissue ® contains nidus

Osteoblastoma

Incidence:
Less than 1% of primary bone tumours
Male = Female (? Male more than Female)
Peak age 10 - 35 years, 80% are less than 30 years old
40 - 50% are vertebral

Clinically

Less intense pain than osteoid osteoma
Occurs in the spine (post elements), often associated with scoliosis and may be neurological signs
May occur in major limb bones

X-Rays

Well demarcated osteolytic lesion sometimes containing flecks of calcification
Less reactive bone than osteoid osteoma
May develop a secondary ABC
May have aggressive features
Bone scan ® intense activity

Pathology

As for Osteoid osteoma but increased size (2 - 10 cm)
Vascular stroma, abundant irregular areas of mineralised bone and osteoid. More organised than an osteoid osteoma
No atypia, no cartilage and occasional mitoses
Vascular tumour +/- haemorrhage and +/- calcification
Texture gritty and friable
Malignant change has been reported
Treatment: Stage 2 lesions: Intra capsular resection ® 20% recurrence
En bloc resection ® no recurrence
Stage 3 lesions: Recurrence after intra capsular or marginal resection
Wide excision ® no recurrence
Use cryotherapy (PMMA) as adjuvant

Prognosis

One case of malignant change reported
Tumours are aggressive locally but do not metastasise

Ossifying Fibroma

Rare lesion characteristically involving the jaw but rarely long bones
Usually eccentric diaphyseal or metaphyseal lesions

Incidence

Male : Female 1:1
Age 0 - 20 years

Clinically

Painless enlarged lump
Present with deformity or pathological fracture

X-Rays

Multi locular appearance
Inter cortical osteolysis ® single or multiple bubble like areas

Pathology

Macroscopically ® dense fibrous coarse tissue +/- reactive bone ® white gritty lesion
Microscopically ® disorganised fibrous tissue and immature bone trabeculae ® woven bone centrally and lamellar bone peripherally
Intra cortical osteolysis ® distortion and thinning of the cortex
They do not heal and may look like monostotic fibrous dysplasia

Treatment

In aggressive phase need wide excision
Active phase ® marginal resection OK
Therefore watch or cast until maturity ® osteotomy for deformity if required ® excision

Periosteal Desmoid

Posteromedial aspect of distal femur ® asymptomatic irregularity, probably related to insertion of adductor magnus
classical site ® nil required

Bone Islands

Normal compact bone
Usually asymptomatic
do not protrude from the surface

Chondroblastoma

Incidence

About 1% of benign bone tumours
Male : Female 2:1
Peak age 10 - 20 years, (rare over 30 years)
50% are in the lower limbs (epiphysial)

Clinically

Present with ache of increasing severity
Usually affects proximal humerus or femur
Site epiphyseal but may expand into metaphysis

X-Rays

Well defined area of rarefaction eccentrically placed in the epiphysis or across the growth plate
No reaction in surrounding bone
50% show central calcification
50% show linear periosteal reaction
Bone scan increased uptake at margins

Pathology

Cell origin:
? enchondral plate
? reticulo histiocytes
May occur in association with an ABC
Usually active benign lesion (Stage 2)
Histology ® pinkish grey tissue, lobulated, may be haemorrhagic, richly cellular multinucleate giant cells with polyclonal or round chondroblasts

Treatment

Marginal excision if not involving the joint
Use cryotherapy if extension intra capsular to avoid excision of joint
Rarely ® aggressive form

Prognosis

Probably no chance of malignant change

Chondro Myxoid Fibroma

Incidence

2% of benign bone tumours
Male more than Female (slight)
Peak age 10 - 30 years (75%)

Clinically

Present with a chronic ache
Usually eccentric metaphyseal lesions
75% lower extremity and 50% tibia

X-Rays

Rounded or oval rare area
Usually eccentrically placed
May cross the growth plate
Sharp outline and sclerotic rim
Scalloped margin and thin cortex

Pathology

May develop from a remnant of the growth plate ?
Localised lesion with peculiarly differentiated connective tissue with chondroid and myxoid elements
Histology ® firm lobulated jelly like areas of mucoid degeneration with areas of chondroid and myxomatous tissue
Contains giant cells, macrophages and monocytes, usually no bone osteoid
Unique histological picture

Treatment

Extra capsular marginal excision ® almost no recurrence
If skeletally immature wait until maturity

Prognosis

Malignant change has been reported ® where possible should be excised

Osteochondroma

Cartilage capped bony projection
Commonest benign tumour of bone

Incidence

Accounts for 45% of benign bone tumours
12% of all bone tumours
Male more than Female (slight)
Age 10 - 40 but most become evident under 20 years
May be solitary or multiple (diaphysial aclasis)
Any bone developing by enchondral ossification may be involved
Diaphysial Aclasis: Autosomal dominant
Disordered enchondral growth
Multiple osteochondromas and disordered metaphyseal growth
Short stature and bowing of limbs
Treat individual lesions as necessary and observe for malignant change
Risk ~ 20% overall or 0.25% per lesion
Trevors Disease: Osteochondroma on epiphysial side of the growth plate

Clinically

Usually become evident in the second decade if not sooner
Present with lump or interference of tendon function
Excise if troublesome in second decade
50% are distal femur, upper tibia or proximal humerus
May be sessile or pedunculated
Active growth during skeletal growth ® become latent
Move towards the diaphysis with growth and usually angle away from the growth plate
During growth period bone scan ® activity at the tip
Increased activity on bone scan after maturity suggests malignant change

Pathology

Normal bone covered by a cap of normal cartilage
? developmental abnormality of juxta epiphysial area of any bone formed in cartilage
Average thickness of the cap is 0.6cm which decreases with maturity
Cartilage cap resembles layers of the normal growth plate

Treatment

Nil required unless symptomatic
Extra capsular marginal excision ® recurrence in ~ 2%
Decreased risk of recurrence if excised after maturity

Prognosis

Risk of malignant change ~ 0.25% in a solitary lesion
Risk of malignant change in diaphysial aclasis 20%
Sarcomatous change usually ® low grade
If cartilage cap more than 8cm diameter or more than 1cm thick suggests sarcomatous change
Fluffy outline on X-Ray also suggestive of sarcomatous change

Enchondroma

Benign tumour of cartilage originating within the medullary cavity
Periosteal form originates in the periosteum and erodes into the cortex

Incidence

Accounts for 10% of benign bone tumours
Greater than 50% occur in small bones of the hands and feet
15% femur and 12% humerus
Male more than Female (slight)
Peak incidence 10 - 50 years
Long bone chondromas usually more than 30 years
May be solitary or multiple (Olliers, Maffuccis)

Clinically

Usually metaphyseal
75% Solitary
60% present as fractures
Present with pathological fracture, lump or as incidental finding
Cortex remains intact unless fracture
X-Rays Scalloped erosions on endosteal surface
May have flecks of calcification
Periosteal form ® shallow crater lined by rim of mature reactive bone

Pathology

Macroscopically ®bluish white well demarcated, well encapsulated and often lobulated gritty tissue
Microscopically ®proliferating rests of mature cartilage cells, nuclei are small and uniform, no atypia and there may be calcification
Need to section all areas of the specimen as sarcomatous change may occur in a benign lesion
Periosteal form less common and has similar pathology but more cellular than usual for a benign lesion. Predilection for proximal humerus near deltoid insertion
Olliers disease ® more cellular and 50% ® malignant transformation
Maffuccis disease ® associated with multiple haemangiomata and associated with nearly 100% malignant change somewhere

Treatment

Curettage and grafting if latent
If active ® recurrence but this may be better than morbidity of en block excision
Periosteal form ® en bloc excision

Prognosis

Risk of malignant change in Olliers or Maffuccis is 50% or higher

Juxta-cortical Chondroma

Rare ~ 20 reported cases

Primary Synovial Chondromatosis

Proliferation of islands of irregular cellular cartilage in the synovium of a joint without underlying arthritis

Incidence

Occurs usually in 2nd to 7th decades

Clinically

Pain and stiffness in a joint of gradual onset
May have locking

X-Rays

Multiple loose bodies

Pathology

Foci of chondromatosis and cytologic aplasia
Frequent local recurrence after resection

Aneurysmal Bone Cyst

Aetiology

? Response to haemorrhage in bone (but no endothelial stroma)
Approx 1/2 arise denovo, 1/2 as part of other lesions (? a reaction to haemorrhage in a preexisting lesion)

Incidence

1 - 5% of benign bone tumours
Age 10 - 30 years
Male : Female 1:2
30 - 40% are grafted onto another primary lesion such as a GCT, chondroblastoma, fibrous dysplasia, chondro myxoid fibroma, EG, simple cyst, osteoblastoma, non ossifying fibroma
50% occur in long bones
30% occur in the spine
Remainder in flat or short bones

Classification (Campanacci)

5 Types
  1. Cyst in centre of bone, little or no expansion
  2. Lesion substitutes whole bone segment
  3. Eccentric inter osseous lesion with little or no expansion
  4. Sub periosteal cyst and superficial erosion of cortex
  5. Periosteum eroded ® expansion into soft tissues

Clinically

Usually occurs in the metaphysis of long bones or in the spine but also tibia, foot, elbow and proximal femur
X-Rays Gross honey comb lesion
Often eccentrically placed
Does not extend to the joint (unlike GCT)
Warm to hot on bone scan

Pathology

Shell of bone with cavernous blood filled spaces separated by a brownish spongy meshwork of vascular or fibrous trabeculae and chronic inflammatory cells
Cavity lined by granulation tissue not vascular endothelium
Fibrous septa containing giant cells and foci of immature bone osteoid
Thin strands of bone cross the lesion

Treatment

Curettage and bone graft ® 20% recurrence
Radiotherapy for older patients with lesions in an inaccessible site
Therefore investigate to exclude other pathology

Prognosis

Secondary ABC ® ?behaviour of primary lesion
Older patient less chance of recurrence

Unicameral Bone Cyst

Definition

Benign developmental lesion of bone characterised by a single fluid filled symmetrically expanding cavity but may be multilocular and even multi cameral after fractures.

Aetiology


Idiopathic
? Traumatic haematoma of bone ® liquefaction
? Vascular abnormalities eg. venous obstruction and increased intra osseous pressure ® fluid transudate and bone necrosis / resorption ® ? response to drilling to decrease pressure
? role of PGE2 by stimulation of osteoclast activating factors may explain role of steroid in its treatment

Incidence

20% of benign bone tumours
Age 5 - 20 years with 70% being 4 - 10 years and 90% less than 20 years
Male : Female 3:1
Usually affect children up to the age of puberty and then become increasingly rare

Classification

Active

Age <10 yrs; Within 1cm of the physis with a pressure of ~ 30cm H2O (> venous pressure, membrane thin and adherent).
Difficult to treat due to location of physis

Latent

Age more than 12 yrs; More than 1cm from the physis and has less than venous pressure, fluid more viscus, membrane thicker and less adherent

Clinically

Metaphyseal lesions and 80% occur in upper femur (25%) or humerus (55%)
Asymptomatic unless fractured and enlarge particularly during periods of active growth
Present as local ache or pathological fracture (90%) or as an incidental finding
X-Rays: Cystic radiolucency on the diaphysial side of the growth plate
Cortex may be thinned and bone expanded with well defined thin sclerotic margin
May have pseudo-loculated appearance secondary to irregular cortical thinning and thin septal ridges
Falling fragment sign typical and the lesion is never wider than epiphysial plate
Bone scan cold or minimal activity unless fractured

Pathology

Microscopically ® fluid fill cyst (transudate) lined with thin fibrous membrane (mesothelium), scattered giant cells, haemosiderin pigment, a few chronic inflammatory cells and lipophages
Histologically may be confused with an ABC or giant cell tumour
Fluid resembles synovial fluid and there may be only a few strands of connective tissue lining the cavity or thick, sometimes vascular membrane

Treatment

Steroid injection may ® ablation
Scaglietti, 1979 ® Methyl prednisolone acetate 80 - 200mg 24% respond to a single injection
40mg/ml methyl prednisolone in fluid aspirated from the cyst (up to a maximum of 3ml)
50 - 75% response rate from each injection cycle is satisfactory and after 3 injections 85-90% of lesions have responded satisfactorily
55% ® complete resolution, 45% some improvement (eg thickening of cortex)
Up to 7 injections used but usually 2 - 3 repeated at intervals of 3 - 6 months
Can inject acutely fractured cysts
Two needles introduced into the lesion®cyst drained®one needle removed and steroid injected
? effect of steroid ® proliferation of metaplastic bone
If persistent curettage and bone grafting usually effective
Treat for deformity and fracture not to obliterate

Prognosis

5 - 15% heal after fracture
Rate of recurrence after curettage 20 - 40 % (dependent on activity)
Recurrence more likely in young patients
Not seen in adults, presumed they disappear spontaneously

Haemangioma of bone

Incidence

Male : Female 1:2
Usually 30 - 50 years

Clinically

Occurring in the spine may ® chronic back ache
Long bones may over grow due to increased blood supply
Usually asymptomatic and solitary, may present as a pathological fracture

X-Rays

Vertical striations without bone expansion (DDx Pagets) and coarse trabecular appearance

Pathology

Vascular hamartoma

Fibrous Cortical defect

Incidence

20% of benign bone tumours
Male more than Female

Clinically

Usually an incidental finding in children
Lucent area in the cortex of a long bone metaphysis
Most heal spontaneously
Larger ones may ® pathological fracture

X-Rays

Margin well defined, sometimes scalloped and often sclerosed

Fibromatosis

Dupuytrens Contracture

Dupuytren ® first accurate description of the disease ® fibroblastic proliferation in the volar surface of the hand ® contracture of fingers as a late but significant result of the disease

Incidence

1 - 2% of population
Affects 1 in 5 people over 65 year
Male : Female 3:1

Clinically

Usually affects right more than left hands
Bilateral in 40 - 60% of cases but usually evident at different stages
Usually most prominent on the ulnar side of the hand with index and thumb least often affected
May ® slowly progressive contracture or aggressive infiltrating lesion
Usually seek medical assistance when ® functional problem

Associations

5 - 20% associated with plantar fibromatosis
4 - 6% penile fibromatosis (Peyronies)
High incidence of knuckle pads
Associate with epileptic and diabetic patients
Chronic alcoholism and cirrhosis
Hereditary predisposition

Knuckle pats

Flat or dome shaped fibrous thickening on dorsal aspect of proximal IP joint or MCP joints
Few symptoms
Usually in 3rd or 4th decades
Males more than Females
Does not occur in the toes
Microscopy resembles palmar fibromatosis

Pathology

Nodules ® fibrous bands ® puckering of the skin and contracture
Histology ® plump immature appearing spindle shaped fibroblasts and collagen in a mucopolysaccharide rich matrix
Increased mitotic activity ® mistake for fibrosarcoma
Increased age of nodule ® decreased cellularity and increased collagen
Fibrosarcoma ® increased pleomorphism, larger nuclei and more mitotic figures, they are also usually deep seated not sub-cutaneous

Treatment

Surgical excision with care to protect digital nerves
May need skin graft to obtain correction and close wound

Plantar Fibromatosis (Ledderhoses disease)

Nodular fibrous proliferation within plantar aponeurosis, less common and less likely to ® digit contracture

Incidence

Male : Female 2:1
Affects both feet in 10 - 15% of cases
Found more commonly in young people, even in people less than 10 yrs
35% evident in people less than 35 years old

Clinically

Nodule usually middle of medial portion of sole of the foot
May ® mild pain after long standing or walking
Associated with penile fibromatosis in 1 - 2%
Also with diabetic and epileptic patients

Pathology

Indistinguishable from the palmar variety

Treatment

Nil unless ® discomfort
Fasciectomy the treatment of choice

Histiocytosis X (= Reticuloendotheliosis)

May be: solitary eosinophilic granuloma or multiple bone and soft tissue lesions
Solitary EG and Hand-Schuller-Christian diseaseare thought to represent a non neoplastic reaction of well differentiated histiocytes to an unknown stimulus
Letterer-Siwe disease is a lymphomatous proliferation of poorly differentiated histiocytes

Aetiology

A non neoplastic proliferation of histiocytes with reactive inflammation. There is an accumulation of abnormal metabolic products of various lipids in the reticuloendothelial cells- lipids are stored in histiocytes -around them an inflammatory granulomatous response occurs.

Incidence

1 - 5% benign bone tumours
Rare ~ 1 / 2,000,000 per year
80% are less than 10 years old (usually 4 - 7 years)
Male = Female (Male slightly more )

Clinically

Can affect just about any bone but skull (10%), femur and spine most commonly
Metaphyseal or diaphysial
Hand-Schuller-Christian Dx- multiple lesions with involvement of liver spleen and pituitary
Letterer-Siwe Dx- <3yo; liver, spleen, skin, CNS involvement- rapidly fatal course -bone involvement uncommon

X-Rays

Mottled lytic defect usually no sclerotic rim
May destroy cortex
Usually endosteal or periosteal reaction
Lesions in flat bones and ribs appear punched out
May appear loculated due to sparing of large trabeculae
Rapid destructive bone lesion ensues
Spinal lesions ® collapse (vertebra plana) which may heal
May be no localised bone lesion but generalised osteoporosis
Bone scan usually hot but variable

Pathology

Probably arise from the reticulo endothelial system
Glistening reddish tissue with flecks of yellow
Infiltration of large reticulum cells (histiocytes) with rounded plump nuclei, diffuse eosinophilic cytoplasm. May be secondary infiltration of eosinophils and less commonly other WBCs may be evident.
Biopsy ® stage of disease (Initially the eosinophilic inflammatory cells dominate; later histiocytes dominate;later fibrocytes dominate with fibrous connective tissue- this is then replaced by bone. ) and estimation of time to resolution

DDX

Ewings , Osteomyelitis, Lymphoma

Treatment

Usually heal spontaneously
? Operation indicated ® curettage and grafting ® diagnosis
May be able to diagnose by aspiration rather than open operation
Steroids
? Place of antibiotics
Radiotherapy for aggressive lesions or for inaccessible disease

Prognosis

Letterer Siwe disease ® worse prognosis often fatal in infancy
Hand Schuller Christian : excellent prognosis if there is no extra-osseous disease
Soft tissue involvement ® worse prognosis
Liver involvement ® 50% die
Lung involvement usually not fatal
Anaemia ® increased mortality and indicates poor prognosis
Skeletal lesions only do not ® death

Adamantinoma

Incidence

Average age usually 35 years
Male more than Female

Clinically

Insidious onset of pain
Slow growing tumour usually seen in jaw or tibia

X-Rays

Characteristic soap bubble cortical lesion with surrounding sclerosis
Cortical thinning with expansion

Pathology

Spindle shaped cells alternating with epithelioid cells
? epithelioid cell origin

Fibrous Dysplasia

Incidence

5 - 20% benign bone lesions
Relatively common and usually monostotic
Affects children and adolescents
Median age at onset 8 years
Male more than Female
Albrights Female more than Male

Clinically

Albrights

Polyostotic disease (unilateral usually)
Skin pigmentation (coast of Maine)
Precocious puberty (endocrinopathy)

Sites


Ribs commonest (40%)
Lower limbs more than upper limbs
Craniofacial ® skull deformity
Epiphyses usually spared
Monostotic disease almost 50% have an asymptomatic rib lesion
Polyostotic ® pain, fracture (85%), deformity and skin pigmentation (coast of Maine)

X-Rays

Ground glass appearance typical
Shepherds crook deformity of proximal femur
Variable appearance with expansion of cortex

Pathology

? developmental hamartoma
Bone replaced by firm, whitish tissue of gritty consistency
Vascular tumour with poorly orientated bone trabeculae separated by fibrous tissue. Bone is woven rather than lamellar and lack of osteoblastic rimming of trabeculae
? developmental hamartoma

Treatment

Monostotic ® curettage and grafting if symptomatic
Polyostotic ® symptomatic treatment
May require osteotomy for deformity or lenthening / shortening procedures

Prognosis

Monostotic lesions cease activity at puberty but may be reactivated by pregnancy
Polyostotic 85% ® pathological fracture
Rarely ® malignant change unless after radiotherapy

Soft Tissue Tumours and Lumps

Ganglion

Differentiate from a synovial cyst which is lined by synovial cells and is an out-pouching of the synovial lining of the joint
Develops secondary to joint pathology

Pathology

Mucinous degeneration within capsule, tendon or tendon sheath
Fibrous walled cyst with clear mucinous fluid usually lacking a recognisable lining of differentiated cells
May arise as hamartoma of synovium or from mucous degeneration of fibrous tissue
Rarely a communication with the joint is demonstrable
May erode adjacent bone ® become intra osseous, the most common site for this being the medial malleolus
Similar lesions seen around the knee usually in proximity to the lateral meniscus

Lipoma

Commonest soft tissue tumour and may occur almost anywhere
Usually more than 50 years old ® painless swelling
May ® sarcomatous change (liposarcoma) indicated by sudden increase in size of lesion usually in thigh or buttock

Fibroma

Usually round with a well defined edge but may be soft with less well defined edge ? increased chance of ® malignant transformation

Neuroma

Not a tumour but an overgrowth of neural connective tissue following trauma eg amputation, pressure ® pain and localised tenderness

Schwannoma

Tumour arising from schwann cells ® little numbness or weakness.
Infiltrates nervous tissue

Neurilemmoma

Similar to schwannoma but grows from the nerve sheath (outside the nerve itself) and is therefore easier to remove

Neurofibroma

Arises from the interstitial tissue of a peripheral nerve
Paraesthesia is not uncommon
Sometimes the nerve root is involved ® cord compression

Glomus Tumour

Rare but very painful
Mixed neural , muscular and vascular elements
Overlying skin often bluish
Often small and never bigger than a pea
Pain and exquisite tenderness with sensitivity to the cold are characteristic
May exist beneath a nail and erode bone
Any part of the body can be affected

Treatment

Excision

Giant Cell Tumour

Incidence

Accounts for ~ 15% of benign bone tumours
4% of all bone tumours
Age usually 20 - 40 years
Most common in 3rd and 4th decade
2% incidence in the skeletally immature
Male : Female 5:6

Classification

(Campanacci)
  1. Lesion confined within bone
  2. Lesion expanding cortex
  3. Breach of cortex
    1. Involvement of the joint
    2. Distant metastases
Ennekings classification could be Stage 1,2 or 3

Clinically

Presents with discomfort or slight swelling
Most common around the knee (50%) but also the pelvis and vertebrae
About 1/3 remain truly benign, 1/3 become locally invasive and 1/3 metastasise
Nearly always located at the very end of a long bone (metaphyseal / epiphyseal)
Pathological fracture occurs in 10 - 15%
Neighbouring joint often irritated (effusion)

X-Rays

Usually well defined lesion in the epiphysis extending up to the joint surface without marginal sclerosis
Junction with normal bone often poorly defined
Cortex thinned and sometimes ballooned
Bone scan warm to hot

Pathology

? arises from mesenchymal cells of connective tissue framework
Soft and friable tumour, the cut surface grey or reddish, areas of necrosis and blood filled cavities. Vascular mononuclear stromal cells, plump spindle shaped cells regularly interspersed with giant osteoclast like cells
May have areas of haemorrhage and necrosis
Up to 50% have soft tissue extension but does not indicate malignancy
1% ® lung metastases

Treatment

Excision
Pathological fracture ® allow to heal before treatment
Surgery is also effective for lung mets
Amputation may be indicated for recurrent aggressive tumours

Prognosis

recurrence after intra-lesional / marginal excision 50 - 60% (curettage)
Sarcomatous transformation in 5 - 10%
May ® metastases without previous malignant change
Stages
  1. 5 - 10% recurrence with intra-lesional or intra capsular resection
  2. Marginal excision or wide if possible (weigh up morbidity of surgery with that of recurrence)
    Cryosurgery / PMMA ® second look at 3-6/12 and graft later
  3. Wide excision best
    Intra capsular ® 30 - 80% recurrence
    Marginal ® 7 - 13% recurrence
Radiotherapy ® increased risk of secondary malignancy

Pigmented Villo-nodular Synovitis

Diffuse proliferation of synovial lining and stroma of synovial joints and tendon sheaths
Usually occurs in the knee as a mon-articular proliferative process

Incidence

2 per 1,000,000 population
Knee involved more frequently than other joints and in diffuse rather than localised form
Male : Female ® 1:1

Clinically

Two forms:
  1. Localised, nodular
  2. Diffuse
May occur anywhere there is synovium (joints, tendon sheaths, or in bursae)
Mon-articular arthritis affecting adults in the 3rd to 4th decade
Onset insidious
50% or less recall an episode of trauma
Associated with a joint effusion

X-Rays

Soft tissue mass
Cysts or bony erosions in ~ 33%
Diffuse bony lesion in ~ 25%
Degenerative joint changes ® cysts both sides of the joint
No abnormality may be evident or only evidence of effusion
Arthrography may identify the synovial mass
Arteriography ® richly vascular soft tissue masses
MRI ® may give typical picture due to haemosiderin

Pathogenesis

Inflammation with haemosiderin laden macrophages
? triggering mechanism
May be a benign neoplastic condition

Pathology

Synovium reddish brown, friable soft nodular masses and villi
Histological lesion characterised by fibrous stroma, deposition of haemosiderin, histiocyte infiltration and giant cells occurring in the synovial membrane of tendon sheaths and large joints
Most lesions are a single nodular outgrowth more likely pedunculated than sessile with a firm elastic consistency
Sub-synovial nodular proliferation of larger round polyhedral or spindle cells with prominent cytoplasm and pale nuclei
Phagocytic, histiocytic cells are also present
Lipid laden foam cells and multi-nucleated giant cells are interspersed with haemosiderin laden cells

Treatment

Recurrence more common in the diffuse form
Local excision acceptable for isolated lesions
Radiotherapy, wide excision arthrodesis and grafting have been used for diffuse disease
None ® universally good results
Radiotherapy best early or when lesions are vascular rather than later when they become fibrosed
Most commonly reported technique is wide synovectomy but ® high incidence of recurrence
Diffuse form associated with significant morbidity but total synovectomy seems the treatment of choice

Multiple Neurofibromatosis (Von Recklinghausens Disease)

Incidence

1 in 3,000
Half are genetic (Autosomal dominant)
Half are new mutations

Clinically

Cafe au lait spots
Skin nodules sometimes (molluscum fibrosum)
Scoliosis present in 30%
Occasionally hypertrophy of one limb

X-Rays

May reveal pressure atrophy of bone
Tumours may ® malignant transformation
Associations with disturbance of bone growth
Anomalies of bone architecture and pseudarthrosis of the tibia and clavicle