EXPLAINING COMMON MALIGNANT BONE TUMOURS

EXPLAINING COMMON MALIGNANT BONE TUMOURS

Common primary malignant bone tumours

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

Osteosarcoma: second commonest primary malignant bone tumour, aggressive and metastasising, affecting the young

Chondrosarcoma: third commonest primary malignant bone tumour

Ewing's sarcoma: second commonest primary bone tumour in children


Adamantinoma: very rare

Malignant fibrous histiocytoma: lytic lesion needing wide resection

lymphoma: primary skeletal lymphoma is usually non-Hodgkin's. Treated by radiotherapy and chemotherapy­

Myeloma: commonest primary malignant bone tumour

Osteosarcoma

• Epidemiology: second commonest primary malignant bone tumour Bi-modal distribution
• 75% of cases in people aged 10-25
• Second smaller peak in incidence in elderly people most of whom have Paget's disease
• Aetiology: 90% idiopathic. Found in the young before epiphyseal closure. 10% secondary to underlying bone disorder (eg Paget's).Genetic basis: surviving retinoblas­toma patients have a 500-fold risk of developing osteosarcoma

• Site: most arise in medullary cavity in metaphyseal ends of long bones. Distal femur ,proximal tibia ,proximal humerus
 proximal femur pelvis

• Pathology: histology reveals malignant osteoblasts producing osteoid. Metastasis and skip lesions are common

• Presentation: painful, enlarging mass. Aggressive tumours mostly with extensive blood­ borne metastaseson diagnosis. 20% have pulmonary metastases on presentation

• Imaging: lytic or sclerotic. Extends through cortex and periosteum forming bulky mass. A triangular shadow is seen between the cortex and raised periosteum (Codman's triangle). Seldom penetrates epiphyseal plate or invades into the joint.

Spiral CT shows pulmonary metastasis in 20% of patients at presentation

• Treatment: advances in combination chemotherapy and limb-sparing surgery significantly improved survival. Resection of pulmonary metastasis is now common practice. 5-year survival rate is 75%. Prognosis is better in young adults, and in those with more distally located tumours
. Multi-focal osteosarcomas and those with a back
ground of Paget'sdisease have poor prognosis

Chondrosarcoma

• Epidemiology: third commonest primary malignant bone tumour

Affects middle-aged and elderly patients

• Aetiology: occurs de novo or as a result of malignant transformation of a previously benign cartilage tumour (eg enchondromas in Ollier's or Maffucci's syndrome

• Site: within the medulla of bone (central) or on bone surface (juxtacortical). Commonly pelvis, ribs, proximal humerus and proximal femur

• Pathology: grading determined by examining cellularity, degree of cytological atypia and mitotic activity. Most are slow growing and are of low to intermediate grade . Seldom metastasise but pulmonary metastasesare most common

• Presentation: pain or pathological fracture

• Imaging: prominent endosteal scalloping and cortical thickening. Destruction with bone expansion

• Treatment: wide surgical resection and limb salvage or amputation. Resection of pulmonary metastasis appropriate in some patients. Radiotherapy and chemotherapy not shown to be effective

• Outcome: determined by the grade of the tumour. 5-year survival rates:

• Grade 1: 90%

• Grade 2: 81%

• Grade 3: 43%


Ewing's sarcoma

• Epidemiology: 2nd commonest primary bone tumour in children. 4th commonest overall. Peak incidence in 20 years

• Site: Diaphysis of long tubular bones especially femur and flat bones of the pelvis

• Pathology: small round cells of unknown origin. 85% have characteristic chromosomal translocation between chromosomes 11 and 22

• Presentation: pain. Enlarging mass. Sometimes associated systemic upset

• Imaging: lytic lesions with permeative margins give (moth-eaten ) appearance (ie wide zone of transition). Characteristic periosteal reaction produces layers of reactive bone deposited with (onion skin) pattern

• Treatment: en bloc resection and chemotherapy Significantly improve 5-year survival rate to 75%

Primitive neuroectodermal tumour (PNET

• Essentially identical to Ewing's sarcoma in all respects except it shows more neural differentiation. Ewing's and PNET may represent different stages of differentiation of a single tumour

Adamantinoma

Very rare age 20-30 years but may occur at any age

Site :90% in tibia

Pathology: lobulated lesion mixed of fibrous and epithelial stroma

Presentation: pain and swelling slowly growing tumour history of preceding tumour are common

Imaging: lobulated lytic area with surrounding sclerotic bone

Treatment: wide resection and reconstruction or amputation

Lymphoma

Affects any age

Site :femur humerus or vertebrae

Pathology: multiple small round cells is usually non hodgkin,s lymphoma

Presentation: pain or soft tissue swelling

Imaging; moth-eaten lytic or sclerotic lesion

Treatment: radiotherapy and chemotherapy

Malignant fibrous histiocytoma

• Epidemiology: affects any age

• Site: metadiaphysis of long bones

• Pathology: consists of spindle cells, histiocyte-type cells probably derived from fibrob­lasts and giant cells. Pulmonary metastases in 30% of cases

• Presentation: pain and swelling

• Imaging: lytic lesion with permeative bone destruction (wide zone of transition). Cortical destruction and minimal periosteal reaction

• Treatment: wide resection. 5-year survival is 30-60%

Myeloma

Common bone tumour age more than 50 years

Site :any bone can be affected

Pathology :monoclonal proliferation of plasma cell B cell producing monoclonal antibody plasma electrophoresis and urine analysis for Bence-Jones protein are useful bone marrow biopsy is diagnostic

Presentation :fatigue pain and weakness

Imaging :lytic lesion with little or no reactive sclerosis typical punched out lesions

Treatment :surgery to treat or to prevent pathological fractures radiotherapy to relieve the pain chemotherapy to suppress the disease bone marrow transplant to provide cure of the disease

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tags:common,bone,tumours,malignant,explaining