bone tumor seen in the first and second decades.
The cyst is filled with blood. 30% are associated or contain elements of another
primary lesion such as a GCT, chondroblastoma, fibrous dysplasia, chondro myxoid
fibroma, EG, simple cyst, osteoblastoma, non ossifying fibroma The ABC can become
large, and can also be the cause of a pathological fracture. Some ABC 's can
be fast growing and locally aggressive. Biopsy and histological diagnosis is
mandatory if ABC is suspected. Treatment is by curettage and packing with bone
chips.
A benign
cartilaginous lesion appearing in adult life, seen often in short tubular
bones e.g. the hand. The lesions are usually single but may be multiple.
Characteristics
- Age: 2nd - 5th decade
- Cartilage
- Short cylindrical bones,often in hand
- Problem: ? Low Grade Chondrosarcoma
|
X-rays show scalloped erosions on endosteal surface. There may be flecks of
calcification. In multiple enchondromatosis (Ollier's disease) there may be associated deformities,
such as genu varus or valgus. In the systemic form (Ollier's), there is a high (10 -20%) incidence of malignant
transformation.
 |
| Multiple enchondromata or Ollier's disease |
Treatment is by curettage and bone grafting. Because many of these may
be low grade malignant chondrosarcoma ( which is difficult to distinguish histologically
from benign enchondroma) additional techniques, such as cryosurgery are also added
to make sure the residual cells are killed.
Non Ossifying Fibroma
 |
Fibrous cortical defect
X-ray features
Margin well defined,
sometimes scalloped,
and often sclerosed |
This is also known as a fibrous
cortical defect or a metaphyseal fibrous defect. Occurs in the metaphysis
in the first two decades of life. Histologically it consists of fibrous tissue.It
is often asymptomatic and found incidentally on X-rays Large lesions may cause
a pathological fracture.
Treatment is only required in a symptomatic lesion. The defect is curetted
and packed with bone.
Osteochondroma
The osteochondroma
is common and presents as a bony outgrowth near an epiphysis.
 |
|
Multiple osteochondromas |
Lesions be single or multiple. It consists of a bony outgrowth with
a cartilage cap. The lesion may have a narrow neck (pedunculated) or
may have a broad base (sessile) Growth stops with skeletal growth. If
the lesion enlarges the cartilage becomes thickened in adult life consider
malignant change in your diagnosis. Malignant change to osteosarcoma
or chondrosarcoma may occur in up to 10% of multiple osteochondromas.
Causes of pain in an Osteochondroma
- Mechanical eg ileotibial band impingement
- Fracture
- Malignant change
Management Not all lesions require excision. Excise symptomatic
lesions and do histology. In multiple osteochondroatosis yearly technetium
scans are done and hot lesions are excised. All symptomatic lesions
must be excised.
Histologically also fibrous tissue. Is a more severe and often systemic form non ossifying fibroma.
It begins in childhood and affects one (monostotic) or many bones. It may cause
deformities such as coxa vara and facial deformities.
X-ray features
Radio lucent or opaque lesions may be lobular or scalloped. The cortex is
eroded and expanded.
Osteoid Osteoma
Osteoid osteoma presents as a sclerotic cortical lesion. It is painful and the pain is relieved by asprin
There is an oval lytic centre known as the nidus.
It is this center that produces benign osteoid.
 |
| Osteoid Osteoma of femoral neck. Notice the sclerosis of the neck and the central nidus |
 |
| Histology - the nidus produces osteoid it may contain giant cells
|
Differential diagnosis of a sclerotic cortical lesion in a child
- Osteoid osteoma
- Stress fracture
- Chronic osteomyelitis
- Malignant tumor e.g. osteosarcoma
Management
To locate the nidus computer tomogrammes are helpful. A technetium scan
will show a hot spot. Excision of the nidus will cure the pain. An en block
excision is done.
Giant Cell Tumours
The Giant Cell Tumor grows
in the epiphysis of adults and undermines the mechanical integrity
of the joint.
 |
|
Giant Cell Tumor |
Treatment
The GCT
consists of giant cells in a spindle cell stroma. The often breaks
through the bone and invades the soft tissue. On rare occasions it
metastasizes to the lungs. The tumor is curetted
and packed with bone. This may fail if it is a major joint and block
excision may be required with arthrodesis or joint replacement.
Chondroblastoma
The chondroblastoma
has a predilection for the epiphysis and is almost always found here.
It does not stretch to the articular surface as the GCT does.
 |
|
Chondroblastoma
- always in the epiphysis, shows areas of calcification |
Peak age incidence 10 to 20 yrs. Almost never undergo malignant transformation.
Treatment
Curettage and bone graft.
Chondromyxiod Fibroma
The Chondromyxoid
Fibroma is composed of myxoid or primitive cartilage and fibrous
tissue. It presents in the second decade or later.
 |
Chondromyxoid fibroma
Eccentrically situated, may stretch to, but not cross, the growth
plate |
It has a very sclerotic endosteal border.
Treatment
Extra capsular marginal excision. Recurrence is rare.
Malignant Bone Tumours
Osteosarcoma
Osteosarcoma
is a primary malignancy of bone. The malignant cells produce osteoid.  Histologically the tumor
is composed of malignant osteoblasts which produce osteoid Most occur in the metaphysis
of long bones especially about he knee. Age - 10 to 20 years. If seen later in
life consider a secondary malignancy ( to Paget's or post irradiation)
It metastases to the lungs and to other bones.
Prognosis
Poor in South Africa (20% 5 yr. survival, because of late presentation). International
experience is towards a 60% survival.
 |
| Histology of an osteosarcoma. Note the malignant osteoid
(pink trabeculae) |
|
 |
X-ray features
Codman's triangle, Sunray spicules |
|
|
|
|
|
Ewing's Sarcoma
Ewing's is a small cell tumor seen in the 10 to 25 yr. age group.
60% occur in the long bones, but the scapula and pelvis are often affected.
 |
|
Ewing's
The tumor lifts the periosteum to produce the typical onion skin appearance |
|
 |
| Ewing's
Small cells of uniform size. On electron microscopy the cells contain
glycogen granules |
|
Ewing's is one of the few tumors that frequently originate in the shaft of long
bones. 50% originate in the diaphysis. It is an osteolytic tumor and has a large
soft tissue component. It may mimic chronic osteomyelitis and even produce a raised
body temperature and ESR as well as white cell count. Histologically the tumor
consists of monotonous sheets of small round cells.
Prognosis:
Poor 30% have lung or bony metastases at time of presentation.
Myeloma
Myeloma
is a common primary tumour from the 5th decade onwards.
Myeloma presents with with lytic bone lesions which commonly lead to pathological
fracture. 
Site
Common in any bone containing red marrow especially flat bones eg pelvis as
well as vertebra. Consider the diagnosis in a vertebral fracture in the elderly.
Typically the vertebra is flattened the so called "wafer" vertebra. If
there is systemic involvement the skull x-ray may show "punched out"
lytic lesions.
Clinically
Affects bone containing red marrow (skull, ribs, vertebrae, sternum, pelvis)
Weakness, bone pain and pathological fractures
Backache is common and may cause root pain and occasionally paraplegia
Anemia, generalised malaise and cachexia
Effects of Myeloma
- Local bone destruction by the tumour
- High plasma protein concentration
- Renal effects of abnornal plasma proteins
|
|
Diagnosis Myeloma
- ESR usually >100 mm/hr
- Serum Electrophoresis
- Urine Bence Jones Protein
- Serum immunoelectrophoresis
- Bone marrow biopsy
- Biopsy - only occasionally needed
|
|
Histology
The tumor is composed of abnormal plasma cells.
If the tumor is localised to one bone it is known as a plasmacytoma
Systemic involvement is known as multiple myeloma
A bone marrow biopsy must be done from the pelvic rim to determine the extent of
spread.
|
| Histology Myeloma
Consists of plasma cells |
|
 |
| Monoclonal peaks are seen in multiple myeloma. Peaks such
as the one on the right do not correspond to the usual Alpha and Beta peaks
|
|
Chondrosarcoma
Chondrosarcoma
usually presents after 6th decade. Characteristically chondrosarcoma is slow growing
and seen proximally in the skeleton e.g. prox. humerus and pelvis.
 |
Chondrosarcoma arising from an Osteochondroma.
Note the fuzziness of the tumour on the left ileum vs. the definite outline
of the osteochondromas of the inferior part of the femur necks |
Chondrosarcoma often arises secondary to other tumours.
- Osteochondromata esp. Multiple
- Enchondroma esp. Ollier's (25%)
- Mafucci (100%)
- Chondroblastoma
- Chondromyxiod fibroma
- Synovial chondromatosis
Treatment
Surgery alone has the ptential of curing
this tumour. It is unresponsive to irradiation and chemotherapy. Block excision
is recommended.
Skeletal Metastases and Pathological Fractures
Metastases
are the most common bone tumours in older patients. They will present to the
orthopaedic surgeon with pain, either because of an actual or threatened pathological
fracture, or will present with a lytic or sclerotic bone lesion. The patient
may have had a primary diagnosed years beforehand, and a history of previous
surgery or investigations must be extracted as such information is not always
volunteered.
| Tumour |
Lytic / Blastic |
| Breast |
Lytic, rarely sclerotic |
| Prostate |
Sclerotic |
| Lung |
Lytic |
| Thyroid |
Lytic, expansile |
| Renal |
Lytic |
Q: When does a patient with a known metastasis require prophylactic fixatation?
A: If the lesion is painful it is likely to be at a pre fracture
stage. If the pain, in a limb with a metastasis, that increases with weight
bearing is an indication for fixation. A lesion that is bigger than 50% of the
diameter of the bone will also need to be fixed.
Once a pathological bone has fractured conservative
treatment will fail and the bone needs ORIF. After fixation all the bone needs
radiotherapy to kill residual cancer cells.
| Mirel's Scoring System
|
| Points |
1 |
2 |
3 |
| Site |
Upper Limb |
Lower Limb |
Peri-trocanteric |
| Pain |
Mild |
Medium |
Severe |
| Lesion |
Blastic |
Mixed |
Lytic |
| Size |
<1/3 |
1/3 to 2/3
|
>2/3 |
A more accurate system of scoring secondary tumors for the risk of pathological fracture
is the method of Mirels.
Points are scored for site, position and whether the tumor is lytic or blastic.
If the score is >7 the tumour needs ORIF.
Occult tumors
An occult metsatasis is obvious on X-ray but there is no primary on physical examination.
Common causes are primaries in the lung, thyroid and kidneys. Special investigations
such as chest X-ray, thyroid scan and abdominal sonar are required. In metastatic
disease a technetium scan is required to see other skeletal mets. and judge the
prognosis.
Treatment
Treatment of secondary tumors is is basically palliative. Fixation is done using he above
guidelines and about 10 days later radiotherapy is given to the limb. Attention is also directed at the primary and
hormonal or chemotherapy given as required.
Spinal metastases with neurological
fallout are sometimes amenable to surgical decompression and stabilisation.
In vertebral metastases due to a high grade tumor and a poor general prognosis
radiotherapy alone is recommended.
Management of Malignant Tumours
Basic Investigations
These are the basic investigations needed needed with most suspected primary tumours
| Investigation |
Reason |
| ESR |
High with sepsis, normal or moderate with tumor |
| Alk Phosphatase |
High - if tumor rapidly replaces bone |
| FBC |
Leucocytosis with sepsis, (sometimes with Ewing's) |
| Chest X-ray |
Pulmonary mets. common in malignant bone tumors |
| X-rays of lesion |
X-ray, features of bone tumor easily recognisable |
Staging
In addition the tumor will have to be staged. These investigations can be done
at the oncology center to which the patient is referred.
Staging Investigations
- Magnetic resonance of tumour site
- CT scan lungs - picks up smaller mets.
- TC Scan - for other bony mets.
- Biopsy
Once the local imaging is done a biopsy can be done and the histology
of the tumour studied
A Staging system such as that of Enneking is used to prognosticate and decide on management.
Treatment
Most malignant bone tumors require surgery and chemotherapy. Radiotherapy
is reserved for iresectable or marginally excised tumours.
Chemotherapy is usually started about 6 weeks preoperatively once the diagnosis
has been confirmed by histology.
Surgery
A wide surgical margin should be achieved.
 |
 |
| Low grade Chondrosarcoma |
After block excision and vascularised fibula graft |
To achieve this aim, either a en block excision with arthrodesis, or custom
mage prosthetic joint is required or an amputation
is needed. The patient needs postoperative chemotherapy too, in most cases.
Block excision can also be used for the treatment of benign, but aggressive
tumours e.g. giant cell tumour about the knee
Histologically also fibrous tissue. Is a more severe and often systemic form non ossifying fibroma.
It begins in childhood and affects one (monostotic) or many bones. It may cause
deformities such as coxa vara and facial deformities.
Histologically the tumor
is composed of malignant osteoblasts which produce osteoid Most occur in the metaphysis
of long bones especially about he knee. Age - 10 to 20 years. If seen later in
life consider a secondary malignancy ( to Paget's or post irradiation)
It metastases to the lungs and to other bones.
