EXPLAINING OF MALIGNANT BONE TUMOURS

EXPLAINING OF MALIGNANT BONE TUMOURS

Introduction

The malignant tumours of the bones are divided into primary malignant bones tumours which arise from the bones  and these are rare tumours and secondary bones tumous which arise due to metastasis from other organs and these are commoner than primary bones tumours

Primary malignant bone tumours

The bones consists of mesenchymal tissue and the tumours of the bones may arise from bone cartilage fat fibrous tissue or endothelium

The histogenetic type of the tumour is depend on the tissue of origin

Specific types of lesions tend to occur in particular bones or area of bones as in the area of maximal growth or remodelling

 Characterized by started as single focus, pesudoencapsulation  formation of zone of reactive tissue around the expanding (lesion) they may spread along fascial planes or remains contained in anatomic compartments which include bones muscle joint skin and subcutaneous tissue and major neurovascular sheath in some cases

Causes of bones tumours

The causes of most bones tumours are unknown

Some may due to genetic mutations and chromosomal aberrations

Clinical features of bones tumours

• Pain characters of bone pain  range from dull ache to severe pain constant boring pain increase or worse at night not related to activity not respond to usual analgesic not relieved by rest in contrast to fracture pain
• Swelling or mass by bleeding into tumours may produce large swelling tumours near a joint may result in joint effusion expanding tumours more noticed early if more distal in the limb thin muscle but in hip and shoulder may obscure small tumours due to its bulky muscle
• Loss of function by neural compression (nerve root or cord) may result in loss of function pathological fractures result in acute loss of function
• Soft tissue tumours often are painless unless there is involvement of neurovascular structures
• Edema of lower limb by compression of veins or lymphatics by the tumours or metastatic invasion
• Malignant soft tissue mass can be firm and fixed to subcutaneous tissue muscle or bone 
• Local warmth is common because malignant lesions induce local (angiogenesis ) formation of new blood vessels
• Pathological fractures with bone destruction 
• Accidentally or incidentally discovers during routine examination or during investigating other problems revealed unsuspected tumours this is very important or may be  due to minor trauma which make attention of the patient or doctor to the tumours
• Systemic or general manifestations like loss of weight loss of appetite fever are very rare to present unless with metastasis

Investigations

Radiological investigations

Plain X rays radiography

• Its simple and most useful study to differentiated diagnosis of bone lesions and detect majority of bone tumours

• It should be interpreted include the following items
• Age of the patients because certain tumours predictive certain ages like ewing,s sarcoma common in children
• Site of the tumours certain tumours predictive special sites like 
• Diaphysis eg. Ewing,s sarcoma and lymphoma also benign tumour as ostoid osteoma
• Epiphysis eg, chondroblastoma and gaint cell tumour
• Metaphysis eg . osteoblastoma ,osteosarcoma,aneurysmal bone cyst fibrous dysplasia non ossifying fibtoma
• There is evidence of matrix production or no as bone formation and calcification
• Growth pattern of the tumours either permeative moth eaten loculated expansile or exophytic
• zone of transition between the normal bone and the tumor which either narrow or well marginated wide or poorly defined sharp or blurred zone
• what is bone involved eg. long bone flat bone skull vertebrae
• Presence of single or multiple lesions 
• associated soft tissue mass 
• Presence or absence of bony reaction to the tumour eg periosteal reaction sclerotic margination or bone destruction

Computerised tomography or CT scanning

• An excellent method for cross sectional examination of bone tumours
• Clear delineated the bone cortex and trabecular and bone destruction
• CT scanning of the lungs are also indicated to screen for pulmonary metastasis which are common CT scanning for abdomen to exclude metastatic disease

Magnetic resonance imaging MRI scanning

• Excellent for as soft tissue contrast
• Excellent for demonstrating tumour spread within intramedullary bone due to the presence of intramedullary fat
• It is essential for investigations of primary bone tumours

Nuclear medicine or isotope bone scanning

• Show extend of skeletal involvement but does not differentiate tumour from fracture or infection
• used to assess  response to treatment or for detection of new bone lesion

Functional nuclear scanning

• Such as positron emission tomography (PET) and Thallium scanning
• they can provide information about the biological or metabolic activity of the tumour and grade of the tumour  and also the area of tumour which either active necrotic or represent recurrent disease

Ultrasound

Useful for imaging superficial soft tissue tumours

 

Laboratory investigations

Routine laboratory studies include

• Complete or full blood count (CBC)( FBC) and differential
• Erythrocyte sedimentation rate (ESR) and C - reactive protein
• Serum alkaline phosphatase calcium and phosphate levels
• Complete urine analysis
• Complete liver function test
• Complete renal or kidney function test

Biopsy

Bone biopsy is taken to determined the nature of the tumour by taken a piece of the tumour tissue and send for histopathological  and immunohistochemical examination as follow

• True - cut needle biopsy
• Percutaneous or core needle biopsy
• Incisional biopsy if the tumour size is large

• Excisional biopsy if tumour size is small
• fine needle aspiration cytology
• Common used are True -cut needle core needle biopsy and incisional biopsy
• It should be done after imaging studies of the tumour to avoid miss interpertation of imaging study and staging of the tumour
• It is should be taken from the periphery of the tumour to avoid central or necrotic area
• Contamination of any other compartment must be avoided
• the bone biopsy cortical window should be small and oval to decrease the risk of pathological fracture

Staging of bones tumours

There are many system of staging the aim from this staging are known the anatomical extend of the tumour it is ability to causes local tissue destruction and its potential to metastasis by either clinical or pathological staging

Clinical staging

 Refers to local and systemic spread of the tumour it is established by examination and imaging studies

Pathological staging

This is based on histology and sometimes immunohistochemistry or genetics of the lesion

The Enneking surgical staging uses three parameters to give a grade from 1 to 3

 Stage IA low grade intracompartmental with no metastasis

Stage IB low grade extracompartmental with no metastasis

Stage II A  high grade intracompartmental with no metastasis 

 Stage IIB high grade extracompartmental with no metastasis
Stage III low or high grade intra or extracompartmental with distant metastasis

Tumour grade

G0  benign
G1 low grade
  G2 high grade

Treatment

   Aim to eradicate the disease  and prevent the recurrence and preserve limb function as possible 

the type treatment depend on the nature of the tumour but common include a combination of several methods as surgery chemotherapy and radiotherapy the treatment has been changed from amputation to limb salvage procedures

Non surgical treatment

• Some malignant tumours are chemosensitive or radiosensitive
• Pre-operative or neoadjuvant chemotherapy may be used with tumours like osteosarcoma and Ewing,s sarcoma to reduce the size of the tumour and make excision of the tumour easy
• Adjuvant chemotherapy has been shown to increase the survival times following resection of these tumours
• Radiotherapy is useful for control of pain and for reducing local recurrence in some tumours like myeloma lymphoma and Ewing,s sarcoma

Methods of surgical treatment

• Intralesional resection or cutettage but this will leave macroscopic remnants of tumour and it is only used for benign tumours
• Marginal resection shells out may leave microscopic remnants of the tumour used in benign tumour
• Wide resection to remove the tumour and the pseudocapsule along with the reactive zone around the tumour and removal all tumour remnants can used in low grade stage I of malignant tumour 
• Radical resection removal of the entire bone or soft tissue compartment to reduce the chance of recurrence
• Amputation if radical resection or reconstruction following radical resection is not possible amputation should be considered

New technique include computer designed prothetic implants which can replace all or part of a bone or a joint

osteochondral allograft new limb lengthening techniques and microvascular technique for free tissue transfer of bone and soft tissue

Prognosis

 Malignant bone tumour remain serious and life threatening disease the prognosis has been improved more than the past

Classification of malignant bone tuomurs

As mentioned above the bone tumours arise from the bone cartilage fat fibrous tissue and endothelium as follow

• Bone forming tumour like osteosarcoma ,paraosreal osteosarcoma, periosteal osteosarcoma, dedifferentiated osteosarcoma
• Cartilage forming tumour like chondrosarcoma ,mesenchymal chondrosarcoma, dedifferentiated chondrosarcoma ,myxoid chondrosarcoma , clear cell chondrosarcoma
• Fat forming tmour like liposarcoma
• Fibrous  or fibro-osseus tumour like fibtosarcoma ,malignant fibrous histiocytoma
• Vascular tumour like hemangioendthelioma, angiosarcoma ,hemangioperictoma
• Gaint cell tumour like malignant gaint cell tumour
• bone marrow tumour like Ewing,s sarcoma myeloma ,lymphoma of the bone , peripheral neurorpithrlioma
• Other or miscellaneous like malignant mesenchymoma , undifferentiated sarcoma, chordoma , adamantinoma , parachordoma 

Common primary malignant bone tumours

  Are osteosarcoma , chondrosarcoma , Ewing,s sarcoma , adamantinoma , malignant fibrous histocytoma , lymphoma , myeloma

For more details about these tumours see here

Secondary bone tumour see here

tags:malignant,explaining,tumours,bone