bone diseases 1 word

د- نجلاء حنون

Lec.1
RADIOLOGY
BONE DISEASE
Imaging technique
I.Plain bone radiograph :
Even with introduction of newer imaging modalities the plain radiograph is a very important investigation in many bone diseases
Radiological X.ray sings of bone disease :-
1.Decrease in bone density , it can be focal or generalized .
-Focal reduction in bone density is referred to as alytic area or bone destruction area .
-Generalized reduction in bone density is referred to as osteopenia until a specific diagnosis such as osteoporosis or osteomalacia can be made .

2-Increase bone density ( sclerosis ) can also be focal or generalized .

3-Periosteal reaction : is an excess bone production by the periosteum occur in response to condition such neoplasm , inflammation & trauma ,several pattern of periosteal reaction has been described but they don’t correlate with specific diagnosis , 4 types of periosteal reaction:
-Smooth solid type (suggested benign process ) .
- Sun-ray type as seen in osteogenic sarcoma.
-Onion skin type as seen in Ewing sarcoma.
-Codmans triangle also seen in osteogenic sarcoma ( suggested aggressive process ) .


4- Cortical thickening : also laying down of new bone by periosteium but the process is slow , new bone of the same density as does the cortex , although it may be thick irregular e.g in chronic osteomylitis , healed trauma .

5. Alteration in trabecular pattern : is a complex response usually involving reduction in the number of trabeculae with an alteration in the remaining trabeculae e.g in osteoporosis & paget disease , in osteoporosis the trabeculae are thin , in paget disease are thick & prominent .

6- Alteration in the shape of bone e.g acromegaly.

7- Alteration in bone age.

II. U/S in musculoskeletal disease :

U/S cannot demonstrate bone pathology but does have a complementary imaging role by:
1. Detecting tenosynovitis , tendon tear & rupture
2.In diagnosis of osteomylitis .
III. radionuclide bone scanning :
Technetium 99m –labelled phosphate complexes given as I.V injection are the agents used for bone scanning ,they are taken selectively by the bone & excreted in the urine .

Indications for radionuclide bone scanning are :

1.Detection of metastasis.
2.Detection of osteomyelitis.
3.Determination of whether alesion is solitary or multifocal
4.Investigation of a clinically suspected bone lesion despite anormal radiograph , such with metastasis , trauma , osteoid osteoma or early osteomylitis .
5.Determination in equivocal cases of whether an abnormality seen on the radiograph is significant or not .
6.Iinvestigation of painful joint prosthesis .
IV. computed tomography in bone disease (CT scan ) :
Is needed in selected cases ,because plain radiograph are usually very informative .
Indication of bone CT scan are :
1.Demonestrating abnormality in the pelvis and spine .
2.Demonstrating the extent & characterization of bone tumour in selected cases to complement MRI .
3.As gide of bone biopsy .


V.MRI (magnetic resonance imaging in bone disease ):
Calcified tissue such as bone produce no signal with MRI but MRI can demonstrate the bone marrow directly make it possible to see full extent of disease such as metastasis , other tumor & infection even in area where bone destruction is not yet evident on plain films or CT scan , MRI is particularly good for showing soft tissue abnormality.
The major indication for MSK MRI are :
1.Demonstrate disc herniation and spinal cord or nerve root compression.
2. Diagnose bone metastasis
3.Show extent of primary bone tumor & demonstrate myloma & lymphoma
4.Iimage soft tissue mass
5. Diagnose osteomylitis & show any soft tissue abnormality
6. to diagnose a vascular necrosis & other joint pathology .

Bone diseases

When considering the diagnosis & differential diagnosis of bone disease , it is convenient to divide disorders in to :
. Solitary lytic or sclerotic lesions .
. Multiple focal lesions.
.Cause generalized reduced or increase bone density.
.Alter the trabecular pattern or change its shape.

Solitary bone lesion are usually one of the following

.Bone tumor: malignant ( primary or secondary ) , benign
. Osteomyelitis.
. Bone cyst, fibrous dysplasia or other non –neoplastic defects of bone.
. Condition of uncertain nature such as langerhans histiocystosis.


The initial radiological decision is usually to try &decide whether the solitary lesion is benign or its aggressive by looking for the following features on plain radiographs & CT :
1.Zone of transition : the edge of any lytic or sclerotic should be examined carefully , there are two extremes : a lesion with well defined sclerotic edge is almost certainly benign ,e.g fibrous cortical defect or bone island , Whereas a lytic area with ill defined edge is likely to be aggressive & include both tumor & infection , in the middle of this spectrum lies the lytic area with no sclerotic rim , which may be benign or malignant lesions , metastasis & myeloma are a frequent cause of this pattern .
2.The adjacent cortex : Any destruction of the adjacent cortex indicate an aggressive lesion such as a malignant tumor or osteomyelitis .
3.Expansion : Bone expansion with an intact well –formed cortex usually indicate a slow growing lesion such as an enchondroma or fibrous dysplasia.
4.Periosteal reaction:The presence of an active periosteal reaction in the absence of trauma usually indicates an aggressive lesion , the causes of localized peiosteal reactions adjacent to a lytic or sclerotic lesions are :
.Osteomyelitis .
.Malignant bone tumour , particularly Ewing sarcoma & osteosarcoma.
.Occasionally metastasis , particularly neuroblastoma.
.Langerhans histiocytosis .
.Trauma .
5. Calcific densities within the lesion: Calcification within an area of bone destruction occurs in specific condition , for example , patchy calcification of popcorn type is usually indicates a cartilage tumour ,whereas diffuse ill-defined calcification suggest osteiod formation and indicate an osteosarcoma .
6. Soft tissue swelling :The presence of a soft tissue mass suggests an aggressive lesion (neoplasm ) , ill defined soft tissue swelling adjacent to a focal destructive lesion suggests infection , some times a tumour arising primarily in the soft tissue may destroy bone by pressure erosion or direct invasion .
7.Site:The site of a lesion is most important as certain lesions tend to occur at certain sites ; for example , osteomyelitis characteristically occur in the metaphyseal areas ( knee & lower tibia ) whereas giant cell tumour are subarticular in position.
Bone tumours
Plain film radiography is the best imaging technique for making a diagnosis , whereas MRI & CT often show the full extent of a tumour to advantage & show the effects on surrounding structure and the relation to the neurovascular bundle , the main role of radionuclide bone scanning is to diagnose metastatic bone disease , metastatic malignant tumour are by far the commonest bone neoplasm , out numbering many times primary malignant tumor .
Primary malignant tumours
On plain films . primary malignant tumours usually have poorly defined margins , often with a wide zone of transition between the normal & abnormal bone . the lesion may destroy the cortex of the bone , a periosteal reaction is often present & a soft tissue mass may be seen .Radionuclide bone scans show substantially increased activity within the lesion MRI is the most accurate technique for showing the local extent of the tumour , i.e extention in to both medullary cavity & soft tissue & show relation ship to adjacent nerve & blood vessels, MRI provide information better than the CT scan .
Osteosarcoma ( osteogenic sarcoma ) :
Occurs mainly in the 5 -20 year-old age group , but is also seen in the elderly following malignant change in paget disease , the tumour often arises in ametaphysis , most commonly around the knee , there is usually bone destruction with new bone formation , & typically a florid speculated periosteal reaction is present , the so called sunray appearance,the tumour may elevate the periosteum to form a codman triangle .
Chondrosarcoma :
Occurs mainly in the 30-50 - year –old age group , most commonly in the pelvic bones , scapulae , humeri & femora . a chondrosarcoma produces a lytic expanding lesion containing flecks of calcium , a sign that indicate its origin from cartilage cells . it is usually less well defined in at least one portion of its outline & it may show aperiosteal reaction , pelvic chondrosarcoma often have large extraosseus components best seen with CT & MRI chondrosarcoma may arise from malignant degeneration of a benign cartilaginous tumour .


Ewing sarcoma :
Is a highly malignant tumour , commonest in children , arising in the shaft of long bones , it produces ill-defined bone destruction with periosteal reaction that is typically onion skin in type .
Giant cell tumour :
Has features of both malignant & benign tumor , it is locally invasive but rarely metastasized, it occurs most commonly around the knee & at the wrist after the epiphyses have fused , it is an expanding destructive lesion , which is subarticular in position , the margin is fairly well defiend but the cortex is thin & may be in places be completely destroyed .
Benign tumour & tumour like condition
In general , benign lesions have an edge which is well demarcated from the normal bone by sclerotic rim , they cause expansion but rarely breach the cortex , there is no soft tissue mass and a periosteal reaction is un usual unless there has been a fracture through the lesion .
Radionuclide scans in benign tumors usually show little or no increase in activity , provided no fracture has occurred .
CT &MRI scanning are infrequently needed in the evaluation of benign tumors .
Enchondromas :
Are seen as lytic expanding lesions most commonly in the bones of the hand . They often contain a few flecks of calcium and frequently present as a pathological fracture .
Fibrous cortical defects ( non ossifying fibromas ) :
Are common chance finding in children and young adults . they produce well – defined lucent areas in the cortex of long bones .

Fibrous dysplasia :

May affect one or several bones . it occur most commonly in the long bones & ribs as lucent area with a well -defined edge and may expand the bone and there may be a sclerotic rim around the lesion.
A simple bone cyst :
Has a wall of fibrous tissue & is filled with fluid . it occurs in children & young adults , most commonly in the humerus & femur . bone cyst form a lucency across the width of the shaft of the bone , with a well –defined edge . the cortex may be thin & the bone expanded. often the first clinical feature is a pathological fracture .
Aneurysmal bone cysts :
Are not true neoplasms , but they probably form secondarily to an underlying primary tumors . mostly they are seen in children and young adults , in the spine , long bones or pelvis . these lesions are purely lytic and cause massive expansion of the cortex , hence the name aneurysmal . they may grow quickly and appear very aggressive but are benign lesion . CT & MRI may show the blood pools within the cyst , the major differential diagnosis is from giant-cell tumor .
Osteoid osteoma :
Is a painful condition found most commonly in the femur & tibia in young adults . it has a characteristic radiological appearance ; a small lucency some times with central specks of calcification , known as a nidus , surrounded by dense sclerotic rim , a periosteal reaction may also be present . CT shows these features to advantages and osteoid osteomas can also be shown by MRI , an important imaging investigation is radionuclide bone scanning which shows marked focal increased activity . radionuclide bone scanning is particularly useful when the osteoid osteomas is difficult to see in plain film .
Osteoma :
Is benign tumor consisting of dense bone , they may occur in the para nasal sinuses .
Eosinophilic granuloma :
Is the mildest & most frequent form of langerhans histiocytosis , it occur in children & young adults & produces lytic lesions which may be single or multiple , more frequently in the skull , pelvis , femur & ribs , extensive lesions may be seen given rise to the so called geographic skull. long bone lesions show bone destruction which may be ill defined having the features of an aggressive lesion or well defined& may have a sclerotic rim , a periosteal re action is some times seen .